Attempts to fix #58 - work with sub-modules

Also fixes issue with nested repos

src/commands/copyMessageToClipboard.ts

@@ -20,6 +20,8 @@ export class CopyMessageToClipboardCommand extends ActiveEditorCommand {
         try {
             // If we don't have an editor then get the message of the last commit to the branch
             if (!uri) {
+                if (!this.git.repoPath) return undefined;
+
                 const log = await this.git.getLogForRepo(this.git.repoPath, undefined, 1);
                 if (!log) return undefined;