message: Fix `<C-^>` when `activeTextEditor` is set to undefined
  Fixes
diff: @@ -231,16 +231,11 @@ export async function activate(context: vscode.ExtensionContext, handleLocal: bo
  // once a new file is opened.
  lastClosedModeHandler = mhPrevious || lastClosedModeHandler;
  - if (vscode.window.activeTextEditor === undefined) {
  - Register.setReadonlyRegister('%', '');
  - return;
  - }
  -
  + const activeTextEditor = vscode.window.activeTextEditor;
  const oldFileRegister = (await Register.get('%'))?.text;
  - const relativePath = vscode.workspace.asRelativePath(
  - vscode.window.activeTextEditor.document.uri,
  - false
  - );
  + const relativePath = activeTextEditor
  + ? vscode.workspace.asRelativePath(activeTextEditor.document.uri, false)
  + : '';
  if (relativePath !== oldFileRegister) {
  if (oldFileRegister && oldFileRegister !== '') {
  