fix for https://github.com/Microsoft/sqlopsstudio/issues/2066 (#677)

src/Microsoft.SqlTools.ServiceLayer/EditData/SmoEditMetadataFactory.cs

@@ -89,10 +89,19 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData
             {
                 Column smoColumn = smoResult.Columns[i];
 
+                string defaultValue = null;
+                try
+                {
                     // The default value may be escaped
-                string defaultValue = smoColumn.DefaultConstraint == null
+                    defaultValue = smoColumn.DefaultConstraint == null
                         ? null
                         : FromSqlScript.UnwrapLiteral(smoColumn.DefaultConstraint.Text);
+                }
+                catch (PropertyCannotBeRetrievedException)
+                {
+                    // This exception will be thrown when the user doesn't have view definition privilege,
+                    // we can ignore it and use null as the default value; 
+                }
 
                 EditColumnMetadata column = new EditColumnMetadata
                 {