Fix #20103

src/vs/workbench/parts/markers/browser/markersTreeController.ts

@@ -123,8 +123,8 @@ export class Controller extends treedefaults.DefaultController {
 					pinned,
 					revealIfVisible: true
 				},
-			}, sideByside).done((editor) => {
-				if (preserveFocus) {
+			}, sideByside).done(editor => {
+				if (editor && preserveFocus) {
 					this.rangeHighlightDecorations.highlightRange(marker, <ICommonCodeEditor>editor.getControl());
 				} else {
 					this.rangeHighlightDecorations.removeHighlightRange();

src/vs/workbench/parts/search/browser/searchViewlet.ts

@@ -1192,8 +1192,8 @@ export class SearchViewlet extends Viewlet {
 				selection,
 				revealIfVisible: true
 			}
-		}, sideBySide).then((editor) => {
-			if (element instanceof Match && preserveFocus) {
+		}, sideBySide).then(editor => {
+			if (editor && element instanceof Match && preserveFocus) {
 				this.viewModel.searchResult.rangeHighlightDecorations.highlightRange({
 					resource,
 					range: element.range()