fix potential npe in editor.hide()

src/vs/workbench/browser/parts/editor/editorGroupsControl.ts

@@ -519,8 +519,12 @@ export class EditorGroupsControl extends Themable implements IEditorGroupsContro
 		// Clear Position
 		this.clearPosition(position);
 
-		// Take editor container offdom and hide
-		editor.getContainer().offDOM().hide();
+		// Take editor container offdom and hide. Check if the editor container
+		// exists in case someone manages to hide an editor before it was created
+		const editorContainer = editor.getContainer();
+		if (editorContainer) {
+			editorContainer.offDOM().hide();
+		}
 
 		// Adjust layout and rochade if instructed to do so
 		if (layoutAndRochade) {