Strict null scripting (#12126)

* strict null scripting

* fix compile

* fix tests

* fix icon

src/sql/workbench/services/objectExplorer/browser/asyncServerTreeDataSource.ts

@@ -52,7 +52,7 @@ export class AsyncServerTreeDataSource implements IAsyncDataSource<ConnectionPro
 				if (element.children) {
 					return element.children;
 				} else {
-					return await this._objectExplorerService.resolveTreeNodeChildren(element.getSession(), element);
+					return await this._objectExplorerService.resolveTreeNodeChildren(element.getSession()!, element);
 				}
 			}
 		} catch (err) {

src/sql/workbench/services/objectExplorer/browser/asyncServerTreeDragAndDrop.ts

@@ -37,15 +37,15 @@ export class AsyncServerTreeDragAndDrop implements ITreeDragAndDrop<ServerTreeEl
 	 * Returns a uri if the given element should be allowed to drag.
 	 * Returns null, otherwise.
 	 */
-	public getDragURI(element: ServerTreeElement): string {
-		return this._dragAndDrop.getDragURI(this._tree, element);
+	public getDragURI(element: ServerTreeElement): string | null {
+		return this._dragAndDrop.getDragURI(this._tree!, element);
 	}
 
 	/**
 	 * Returns a label(name) to display when dragging the element.
 	 */
 	public getDragLabel(elements: ServerTreeElement[]): string {
-		return this._dragAndDrop.getDragLabel(this._tree, elements);
+		return this._dragAndDrop.getDragLabel(this._tree!, elements);
 	}
 
 	/**
@@ -54,17 +54,17 @@ export class AsyncServerTreeDragAndDrop implements ITreeDragAndDrop<ServerTreeEl
 	public onDragStart(dragAndDropData: IDragAndDropData, originalEvent: DragEvent): void {
 		// Force the event cast while in preview - we don't use any of the mouse properties on the
 		// implementation so this is fine for now
-		return this._dragAndDrop.onDragStart(this._tree, dragAndDropData, <any>originalEvent);
+		return this._dragAndDrop.onDragStart(this._tree!, dragAndDropData, <any>originalEvent);
 	}
 
-	public onDragOver(data: IDragAndDropData, targetElement: ServerTreeElement, targetIndex: number, originalEvent: DragEvent): boolean | ITreeDragOverReaction {
+	public onDragOver(data: IDragAndDropData, targetElement: ServerTreeElement | undefined, targetIndex: number, originalEvent: DragEvent): boolean | ITreeDragOverReaction {
 		// Dropping onto an empty space (undefined targetElement) we treat as wanting to move into the root connection group
 		if (!targetElement) {
 			targetElement = this._tree?.getInput();
 		}
 		// Force the event cast while in preview - we don't use any of the mouse properties on the
 		// implementation so this is fine for now
-		const canDragOver = this._dragAndDrop.onDragOver(this._tree, data, targetElement, <any>originalEvent);
+		const canDragOver = this._dragAndDrop.onDragOver(this._tree!, data, targetElement, <any>originalEvent);
 
 		if (canDragOver.accept) {
 			return TreeDragOverReactions.acceptBubbleDown(canDragOver.autoExpand);
@@ -76,14 +76,14 @@ export class AsyncServerTreeDragAndDrop implements ITreeDragAndDrop<ServerTreeEl
 	/**
 	 * Handle a drop in the server tree.
 	 */
-	public drop(data: IDragAndDropData, targetElement: ServerTreeElement, targetIndex: number, originalEvent: DragEvent): void {
+	public drop(data: IDragAndDropData, targetElement: ServerTreeElement | undefined, targetIndex: number, originalEvent: DragEvent): void {
 		// Dropping onto an empty space (undefined targetElement) we treat as wanting to move into the root connection group
 		if (!targetElement) {
 			targetElement = this._tree?.getInput();
 		}
 		// Force the event cast while in preview - we don't use any of the mouse properties on the
 		// implementation so this is fine for now
-		this._dragAndDrop.drop(this._tree, data, targetElement, <any>originalEvent);
+		this._dragAndDrop.drop(this._tree!, data, targetElement, <any>originalEvent);
 	}
 
 	public onDragEnd(originalEvent: DragEvent): void {
@@ -102,7 +102,7 @@ export class AsyncRecentConnectionsDragAndDrop implements ITreeDragAndDrop<Serve
 			return (<ConnectionProfile>element).id;
 		}
 		else if (element instanceof ConnectionProfileGroup) {
-			return (<ConnectionProfileGroup>element).id;
+			return (<ConnectionProfileGroup>element).id ?? null;
 		}
 		return null;
 	}
@@ -117,7 +117,7 @@ export class AsyncRecentConnectionsDragAndDrop implements ITreeDragAndDrop<Serve
 		else if (elements[0] instanceof ConnectionProfileGroup) {
 			return elements[0].name;
 		}
-		return undefined;
+		return '';
 	}
 
 	/**

src/sql/workbench/services/objectExplorer/browser/asyncServerTreeIdentityProvider.ts

@@ -8,6 +8,6 @@ import { ServerTreeElement } from 'sql/workbench/services/objectExplorer/browser
 
 export class AsyncServerTreeIdentityProvider implements IIdentityProvider<ServerTreeElement> {
 	getId(element: ServerTreeElement): { toString(): string; } {
-		return element.id;
+		return element.id!;
 	}
 }

src/sql/workbench/services/objectExplorer/browser/asyncServerTreeRenderer.ts

@@ -8,7 +8,7 @@ import 'vs/css!./media/objectTypes/objecttypes';
 import * as dom from 'vs/base/browser/dom';
 import { localize } from 'vs/nls';
 import { ConnectionProfileGroup } from 'sql/platform/connection/common/connectionProfileGroup';
-import { ConnectionProfile } from 'sql/platform/connection/common/connectionProfile';
+import { ConnectionProfile, IconPath } from 'sql/platform/connection/common/connectionProfile';
 import { IConnectionManagementService } from 'sql/platform/connection/common/connectionManagement';
 import { TreeNode } from 'sql/workbench/services/objectExplorer/common/treeNode';
 import { iconRenderer } from 'sql/workbench/services/objectExplorer/browser/iconRenderer';
@@ -22,6 +22,7 @@ import { IListAccessibilityProvider } from 'vs/base/browser/ui/list/listWidget';
 import { ServerTreeRenderer } from 'sql/workbench/services/objectExplorer/browser/serverTreeRenderer';
 import { ServerTreeElement } from 'sql/workbench/services/objectExplorer/browser/asyncServerTree';
 import { DefaultServerGroupColor } from 'sql/workbench/services/serverGroup/common/serverGroupViewModel';
+import { withNullAsUndefined } from 'vs/base/common/types';
 
 class ConnectionProfileGroupTemplate extends Disposable {
 	private _root: HTMLElement;
@@ -31,7 +32,7 @@ class ConnectionProfileGroupTemplate extends Disposable {
 		container: HTMLElement
 	) {
 		super();
-		container.parentElement.classList.add('server-group');
+		container.parentElement!.classList.add('server-group');
 		container.classList.add('server-group');
 		this._root = dom.append(container, dom.$('.server-group'));
 		this._nameContainer = dom.append(this._root, dom.$('span.name'));
@@ -89,7 +90,7 @@ class ConnectionProfileTemplate extends Disposable {
 		@IConnectionManagementService private _connectionManagementService: IConnectionManagementService
 	) {
 		super();
-		container.parentElement.classList.add('connection-profile');
+		container.parentElement!.classList.add('connection-profile');
 		this._root = dom.append(container, dom.$('.connection-tile'));
 		this._icon = dom.append(this._root, dom.$('div.icon server-page'));
 		this._connectionStatusBadge = dom.append(this._icon, dom.$('div.connection-status-badge'));
@@ -98,16 +99,15 @@ class ConnectionProfileTemplate extends Disposable {
 
 	set(element: ConnectionProfile) {
 		if (!this._isCompact) {
-			let iconPath: IconPath = getIconPath(element, this._connectionManagementService);
+			let iconPath: IconPath | undefined = getIconPath(element, this._connectionManagementService);
 			if (this._connectionManagementService.isConnected(undefined, element)) {
 				this._connectionStatusBadge.classList.remove('disconnected');
 				this._connectionStatusBadge.classList.add('connected');
-				renderServerIcon(this._icon, iconPath);
 			} else {
 				this._connectionStatusBadge.classList.remove('connected');
 				this._connectionStatusBadge.classList.add('disconnected');
-				renderServerIcon(this._icon, iconPath);
 			}
+			renderServerIcon(this._icon, iconPath);
 		}
 
 		let label = element.title;
@@ -156,7 +156,7 @@ class TreeNodeTemplate extends Disposable {
 	set(element: TreeNode) {
 		// Use an explicitly defined iconType first. If not defined, fall back to using nodeType and
 		// other compount indicators instead.
-		let iconName: string = undefined;
+		let iconName: string | undefined = undefined;
 		if (element.iconType) {
 			iconName = (typeof element.iconType === 'string') ? element.iconType : element.iconType.id;
 		} else {
@@ -171,7 +171,7 @@ class TreeNodeTemplate extends Disposable {
 
 		let tokens: string[] = [];
 		for (let index = 1; index < this._icon.classList.length; index++) {
-			tokens.push(this._icon.classList.item(index));
+			tokens.push(this._icon.classList.item(index)!);
 		}
 		this._icon.classList.remove(...tokens);
 		this._icon.classList.add('icon');
@@ -229,7 +229,7 @@ export class ServerTreeAccessibilityProvider implements IListAccessibilityProvid
 
 	getAriaLabel(element: ServerTreeElement): string | null {
 		if (element instanceof ConnectionProfileGroup) {
-			return element.fullName;
+			return element.fullName ?? null;
 		} else if (element instanceof ConnectionProfile) {
 			return element.title;
 		}
@@ -240,22 +240,22 @@ export class ServerTreeAccessibilityProvider implements IListAccessibilityProvid
 /**
  * Returns the first parent which contains the className
  */
-function findParentElement(container: HTMLElement, className: string): HTMLElement {
-	let currentElement = container;
+function findParentElement(container: HTMLElement, className: string): HTMLElement | undefined {
+	let currentElement: HTMLElement | null = container;
 	while (currentElement) {
 		if (currentElement.className.indexOf(className) > -1) {
 			break;
 		}
 		currentElement = currentElement.parentElement;
 	}
-	return currentElement;
+	return withNullAsUndefined(currentElement);
 }
 
-function getIconPath(connection: ConnectionProfile, connectionManagementService: IConnectionManagementService): IconPath {
+function getIconPath(connection: ConnectionProfile, connectionManagementService: IConnectionManagementService): IconPath | undefined {
 	if (!connection) { return undefined; }
 
-	if (connection['iconPath']) {
-		return connection['iconPath'];
+	if (connection.iconPath) {
+		return connection.iconPath;
 	}
 
 	let iconId = connectionManagementService.getConnectionIconId(connection.id);
@@ -264,8 +264,8 @@ function getIconPath(connection: ConnectionProfile, connectionManagementService:
 	let providerProperties = connectionManagementService.getProviderProperties(connection.providerName);
 	if (!providerProperties) { return undefined; }
 
-	let iconPath: IconPath = undefined;
-	let pathConfig: URI | IconPath | { id: string, path: IconPath }[] = providerProperties['iconPath'];
+	let iconPath: IconPath | undefined = undefined;
+	let pathConfig: URI | IconPath | { id: string, path: IconPath }[] | undefined = providerProperties['iconPath'];
 	if (Array.isArray(pathConfig)) {
 		for (const e of pathConfig) {
 			if (!e.id || e.id === iconId) {
@@ -274,25 +274,18 @@ function getIconPath(connection: ConnectionProfile, connectionManagementService:
 				break;
 			}
 		}
-	} else if (pathConfig['light']) {
-		iconPath = pathConfig as IconPath;
-		connection['iconPath'] = iconPath;
+	} else if (URI.isUri(pathConfig)) {
+		iconPath = { light: pathConfig, dark: pathConfig };
+		connection.iconPath = iconPath;
 	} else {
-		let singlePath = pathConfig as URI;
-		iconPath = { light: singlePath, dark: singlePath };
-		connection['iconPath'] = iconPath;
+		connection.iconPath = pathConfig;
 	}
 	return iconPath;
 }
 
-function renderServerIcon(element: HTMLElement, iconPath: IconPath): void {
+function renderServerIcon(element: HTMLElement, iconPath?: IconPath): void {
 	if (!element) { return; }
 	if (iconPath) {
 		iconRenderer.putIcon(element, iconPath);
 	}
 }
-
-interface IconPath {
-	light: URI;
-	dark: URI;
-}

src/sql/workbench/services/objectExplorer/browser/dragAndDropController.ts

@@ -28,6 +28,8 @@ export function supportsFolderNodeNameDrop(nodeId: string, label: string): boole
 	return false;
 }
 
+function escapeString(input: string): string;
+function escapeString(input: undefined): undefined;
 function escapeString(input: string | undefined): string | undefined {
 	return input?.replace(/]/g, ']]');
 }
@@ -46,22 +48,22 @@ export class ServerTreeDragAndDrop implements IDragAndDrop {
 	 * Returns a uri if the given element should be allowed to drag.
 	 * Returns null, otherwise.
 	 */
-	public getDragURI(tree: AsyncServerTree | ITree, element: any): string {
+	public getDragURI(tree: AsyncServerTree | ITree, element: any): string | null {
 		if (element) {
 			if (element instanceof ConnectionProfile) {
-				return (<ConnectionProfile>element).id;
+				return element.id;
 			} else if (element instanceof ConnectionProfileGroup) {
-				return (<ConnectionProfileGroup>element).id;
+				return element.id ?? null;
 			} else if (supportsNodeNameDrop(element.nodeTypeId)) {
 				return (<TreeNode>element).id;
 			} else if (supportsFolderNodeNameDrop(element.nodeTypeId, element.label) && element.children) {
 				return (<TreeNode>element).id;
 			} else {
-				return undefined;
+				return null;
 			}
 		}
 		else {
-			return undefined;
+			return null;
 		}
 	}
 
@@ -78,11 +80,11 @@ export class ServerTreeDragAndDrop implements IDragAndDrop {
 				return elements[0].label;
 			}
 			else {
-				return undefined;
+				return '';
 			}
 		}
 		else {
-			return undefined;
+			return '';
 		}
 	}
 
@@ -125,7 +127,7 @@ export class ServerTreeDragAndDrop implements IDragAndDrop {
 			return element.connection.providerName;
 		}
 
-		return this.getProviderNameFromElement(element.parent);
+		return this.getProviderNameFromElement(element.parent!);
 	}
 
 
@@ -133,7 +135,7 @@ export class ServerTreeDragAndDrop implements IDragAndDrop {
 		let canDragOver: boolean = true;
 
 		if (source instanceof ConnectionProfile) {
-			if (!this._connectionManagementService.canChangeConnectionConfig(source, targetConnectionProfileGroup.id)) {
+			if (!this._connectionManagementService.canChangeConnectionConfig(source, targetConnectionProfileGroup.id!)) {
 				canDragOver = false;
 			}
 		} else if (source instanceof ConnectionProfileGroup) {
@@ -158,7 +160,7 @@ export class ServerTreeDragAndDrop implements IDragAndDrop {
 			// Verify if the connection can be moved to the target group
 			const source = data.getData()[0];
 			if (source instanceof ConnectionProfile) {
-				if (!this._connectionManagementService.canChangeConnectionConfig(source, targetConnectionProfileGroup.id)) {
+				if (!this._connectionManagementService.canChangeConnectionConfig(source, targetConnectionProfileGroup.id!)) {
 					canDragOver = false;
 				}
 			} else if (source instanceof ConnectionProfileGroup) {
@@ -201,7 +203,7 @@ export class ServerTreeDragAndDrop implements IDragAndDrop {
 
 				if (source instanceof ConnectionProfile) {
 					// Change group id of profile
-					this._connectionManagementService.changeGroupIdForConnection(source, targetConnectionProfileGroup.id).then(() => {
+					this._connectionManagementService.changeGroupIdForConnection(source, targetConnectionProfileGroup.id!).then(() => {
 						if (tree) {
 							TreeUpdateUtils.registeredServerUpdate(tree, self._connectionManagementService, targetConnectionProfileGroup);
 						}
@@ -224,13 +226,13 @@ export class ServerTreeDragAndDrop implements IDragAndDrop {
 		TreeUpdateUtils.isInDragAndDrop = false;
 	}
 
-	private getTargetGroup(targetElement: any): ConnectionProfileGroup {
+	private getTargetGroup(targetElement: ConnectionProfileGroup | ConnectionProfile): ConnectionProfileGroup {
 		let targetConnectionProfileGroup: ConnectionProfileGroup;
 		if (targetElement instanceof ConnectionProfile) {
-			targetConnectionProfileGroup = (<ConnectionProfile>targetElement).getParent();
+			targetConnectionProfileGroup = targetElement.getParent()!;
 		}
 		else {
-			targetConnectionProfileGroup = <ConnectionProfileGroup>targetElement;
+			targetConnectionProfileGroup = targetElement;
 		}
 
 		return targetConnectionProfileGroup;
@@ -256,12 +258,12 @@ export class RecentConnectionsDragAndDrop implements IDragAndDrop {
 	 * Returns a uri if the given element should be allowed to drag.
 	 * Returns null, otherwise.
 	 */
-	public getDragURI(tree: ITree, element: any): string {
+	public getDragURI(tree: ITree, element: any): string | null {
 		if (element instanceof ConnectionProfile) {
 			return (<ConnectionProfile>element).id;
 		}
 		else if (element instanceof ConnectionProfileGroup) {
-			return (<ConnectionProfileGroup>element).id;
+			return (<ConnectionProfileGroup>element).id ?? null;
 		}
 		return null;
 	}
@@ -276,7 +278,7 @@ export class RecentConnectionsDragAndDrop implements IDragAndDrop {
 		else if (elements[0] instanceof ConnectionProfileGroup) {
 			return (<ConnectionProfileGroup>elements[0]).name;
 		}
-		return undefined;
+		return '';
 	}
 
 	/**

src/sql/workbench/services/objectExplorer/browser/iconRenderer.ts

@@ -10,11 +10,11 @@ import { URI } from 'vs/base/common/uri';
 class IconRenderer {
 	private iconRegistered: Set<string> = new Set<string>();
 
-	public registerIcon(path: URI | IconPath): string {
+	public registerIcon(path: URI | IconPath): string | undefined {
 		if (!path) { return undefined; }
 		let iconPath: IconPath = this.toIconPath(path);
-		let iconUid: string = this.getIconUid(iconPath);
-		if (!this.iconRegistered.has(iconUid)) {
+		let iconUid: string | undefined = this.getIconUid(iconPath);
+		if (iconUid && !this.iconRegistered.has(iconUid)) {
 			createCSSRule(`.icon#${iconUid}`, `background: ${asCSSUrl(iconPath.light || iconPath.dark)} center center no-repeat`);
 			createCSSRule(`.vs-dark .icon#${iconUid}, .hc-black .icon#${iconUid}`, `background: ${asCSSUrl(iconPath.dark)} center center no-repeat`);
 			this.iconRegistered.add(iconUid);
@@ -22,30 +22,30 @@ class IconRenderer {
 		return iconUid;
 	}
 
-	public getIconUid(path: URI | IconPath): string {
+	public getIconUid(path: URI | IconPath): string | undefined {
 		if (!path) { return undefined; }
 		let iconPath: IconPath = this.toIconPath(path);
 		return `icon${hash(iconPath.light.toString() + iconPath.dark.toString())}`;
 	}
 
 	private toIconPath(path: URI | IconPath): IconPath {
-		if (path['light']) {
-			return path as IconPath;
-		} else {
-			let singlePath = path as URI;
+		if (URI.isUri(path)) {
+			let singlePath = path;
 			return { light: singlePath, dark: singlePath };
+		} else {
+			return path;
 		}
 	}
 
 	public putIcon(element: HTMLElement, path: URI | IconPath): void {
 		if (!element || !path) { return undefined; }
-		let iconUid: string = this.registerIcon(path);
-		element.id = iconUid;
+		let iconUid: string | undefined = this.registerIcon(path);
+		element.id = iconUid ?? '';
 	}
 
 	public removeIcon(element: HTMLElement): void {
 		if (!element) { return undefined; }
-		element.id = undefined;
+		element.id = '';
 	}
 }
 
@@ -117,9 +117,9 @@ class BadgeRenderer {
 
 	public removeBadge(element: HTMLElement, badgeClass: string): void {
 		let children: HTMLCollection = element.children;
-		let current = children[0];
+		let current: Element | null = children[0];
 		while (current) {
-			let next = current.nextElementSibling;
+			let next: Element | null = current.nextElementSibling;
 			if (current.classList.contains(badgeClass)) {
 				current.remove();
 				break;

src/sql/workbench/services/objectExplorer/browser/recentConnectionDataSource.ts

@@ -19,10 +19,8 @@ export class RecentConnectionDataSource implements IDataSource {
 	public getId(tree: ITree, element: any): string {
 		if (element instanceof ConnectionProfile) {
 			return (<ConnectionProfile>element).id;
-		} else if (element instanceof ConnectionProfileGroup) {
-			return (<ConnectionProfileGroup>element).id;
 		} else {
-			return undefined;
+			return (<ConnectionProfileGroup>element).id!;
 		}
 	}
 
@@ -63,4 +61,4 @@ export class RecentConnectionDataSource implements IDataSource {
 			return Promise.resolve(null);
 		}
 	}
-}
+}

src/sql/workbench/services/objectExplorer/browser/serverTreeController.ts

@@ -74,7 +74,7 @@ export class ServerTreeController extends treedefaults.DefaultController {
 			context.nodeInfo = element.toNodeInfo();
 			// Note: getting DB name before, but intentionally not using treeUpdateUtils.getConnectionProfile as it replaces
 			// the connection ID with a new one. This breaks a number of internal tasks
-			context.connectionProfile = element.getConnectionProfile().toIConnectionProfile();
+			context.connectionProfile = element.getConnectionProfile()!.toIConnectionProfile();
 			context.connectionProfile.databaseName = element.getDatabaseName();
 			actionContext = context;
 		} else if (element instanceof ConnectionProfile) {

src/sql/workbench/services/objectExplorer/browser/serverTreeDataSource.ts

@@ -30,13 +30,7 @@ export class ServerTreeDataSource implements IDataSource {
 	 * No more than one element may use a given identifier.
 	 */
 	public getId(tree: ITree, element: any): string {
-		if (element instanceof ConnectionProfile
-			|| element instanceof ConnectionProfileGroup
-			|| element instanceof TreeNode) {
-			return element.id;
-		} else {
-			return undefined;
-		}
+		return element.id;
 	}
 
 	/**
@@ -67,7 +61,7 @@ export class ServerTreeDataSource implements IDataSource {
 				return node.children;
 			} else {
 				try {
-					return this._objectExplorerService.resolveTreeNodeChildren(node.getSession(), node);
+					return this._objectExplorerService.resolveTreeNodeChildren(node.getSession()!, node);
 				} catch (expandError) {
 					await node.setExpandedState(TreeItemCollapsibleState.Collapsed);
 					node.errorStateMessage = expandError;

src/sql/workbench/services/objectExplorer/browser/serverTreeRenderer.ts

@@ -16,6 +16,7 @@ import { InputBox } from 'vs/base/browser/ui/inputbox/inputBox';
 import { badgeRenderer, iconRenderer } from 'sql/workbench/services/objectExplorer/browser/iconRenderer';
 import { URI } from 'vs/base/common/uri';
 import { DefaultServerGroupColor } from 'sql/workbench/services/serverGroup/common/serverGroupViewModel';
+import { withNullAsUndefined } from 'vs/base/common/types';
 
 export interface IConnectionTemplateData {
 	root: HTMLElement;
@@ -132,7 +133,7 @@ export class ServerTreeRenderer implements IRenderer {
 	private renderObjectExplorer(treeNode: TreeNode, templateData: IObjectExplorerTemplateData): void {
 		// Use an explicitly defined iconType first. If not defined, fall back to using nodeType and
 		// other compount indicators instead.
-		let iconName: string = undefined;
+		let iconName: string | undefined = undefined;
 		if (treeNode.iconType) {
 			iconName = (typeof treeNode.iconType === 'string') ? treeNode.iconType : treeNode.iconType.id;
 		} else {
@@ -147,7 +148,7 @@ export class ServerTreeRenderer implements IRenderer {
 
 		let tokens: string[] = [];
 		for (let index = 1; index < templateData.icon.classList.length; index++) {
-			tokens.push(templateData.icon.classList.item(index));
+			tokens.push(templateData.icon.classList.item(index)!);
 		}
 		templateData.icon.classList.remove(...tokens);
 		templateData.icon.classList.add('icon');
@@ -162,11 +163,11 @@ export class ServerTreeRenderer implements IRenderer {
 		templateData.root.title = treeNode.label;
 	}
 
-	private getIconPath(connection: ConnectionProfile): IconPath {
+	private getIconPath(connection: ConnectionProfile): IconPath | undefined {
 		if (!connection) { return undefined; }
 
-		if (connection['iconPath']) {
-			return connection['iconPath'];
+		if (connection.iconPath) {
+			return connection.iconPath;
 		}
 
 		let iconId = this._connectionManagementService.getConnectionIconId(connection.id);
@@ -175,8 +176,8 @@ export class ServerTreeRenderer implements IRenderer {
 		let providerProperties = this._connectionManagementService.getProviderProperties(connection.providerName);
 		if (!providerProperties) { return undefined; }
 
-		let iconPath: IconPath = undefined;
-		let pathConfig: URI | IconPath | { id: string, path: IconPath }[] = providerProperties['iconPath'];
+		let iconPath: IconPath | undefined = undefined;
+		let pathConfig: URI | IconPath | { id: string, path: IconPath }[] | undefined = providerProperties.iconPath;
 		if (Array.isArray(pathConfig)) {
 			for (const e of pathConfig) {
 				if (!e.id || e.id === iconId) {
@@ -185,18 +186,18 @@ export class ServerTreeRenderer implements IRenderer {
 					break;
 				}
 			}
-		} else if (pathConfig['light']) {
-			iconPath = pathConfig as IconPath;
-			connection['iconPath'] = iconPath;
-		} else {
+		} else if (URI.isUri(pathConfig)) {
 			let singlePath = pathConfig as URI;
 			iconPath = { light: singlePath, dark: singlePath };
-			connection['iconPath'] = iconPath;
+			connection.iconPath = iconPath;
+		} else {
+			iconPath = pathConfig as IconPath;
+			connection.iconPath = iconPath;
 		}
 		return iconPath;
 	}
 
-	private renderServerIcon(element: HTMLElement, iconPath: IconPath, isConnected: boolean): void {
+	private renderServerIcon(element: HTMLElement, iconPath: IconPath | undefined, isConnected: boolean): void {
 		if (!element) { return; }
 		if (iconPath) {
 			iconRenderer.putIcon(element, iconPath);
@@ -209,7 +210,7 @@ export class ServerTreeRenderer implements IRenderer {
 
 	private renderConnection(connection: ConnectionProfile, templateData: IConnectionTemplateData): void {
 		if (!this._isCompact) {
-			let iconPath: IconPath = this.getIconPath(connection);
+			let iconPath = this.getIconPath(connection);
 			if (this._connectionManagementService.isConnected(undefined, connection)) {
 				templateData.icon.classList.remove('disconnected');
 				templateData.icon.classList.add('connected');
@@ -252,15 +253,15 @@ export class ServerTreeRenderer implements IRenderer {
 	/**
 	 * Returns the first parent which contains the className
 	 */
-	private findParentElement(container: HTMLElement, className: string): HTMLElement {
-		let currentElement = container;
+	private findParentElement(container: HTMLElement, className: string): HTMLElement | undefined {
+		let currentElement: HTMLElement | null = container;
 		while (currentElement) {
 			if (currentElement.className.indexOf(className) > -1) {
 				break;
 			}
 			currentElement = currentElement.parentElement;
 		}
-		return currentElement;
+		return withNullAsUndefined(currentElement);
 	}
 
 	public disposeTemplate(tree: ITree, templateId: string, templateData: any): void {

src/sql/workbench/services/objectExplorer/browser/treeCreationUtils.ts

@@ -142,5 +142,5 @@ export class TreeCreationUtils {
 }
 
 function useAsyncServerTree(configurationService: IConfigurationService): boolean {
-	return configurationService.getValue('workbench.enablePreviewFeatures') && configurationService.getValue('serverTree.useAsyncServerTree');
+	return configurationService.getValue<boolean>('workbench.enablePreviewFeatures') && configurationService.getValue<boolean>('serverTree.useAsyncServerTree');
 }