Prevent terminal waitOnExit from bubbling up

Fixes #19397

src/vs/workbench/parts/terminal/electron-browser/terminalInstance.ts

@@ -418,8 +418,9 @@ export class TerminalInstance implements ITerminalInstance {
 			this._xterm.writeln(nls.localize('terminal.integrated.waitOnExit', 'Press any key to close the terminal'));
 			// Disable all input if the terminal is exiting and listen for next keypress
 			this._xterm.setOption('disableStdin', true);
-			this._processDisposables.push(DOM.addDisposableListener(this._xterm.textarea, 'keypress', () => {
+			this._processDisposables.push(DOM.addDisposableListener(this._xterm.textarea, 'keypress', (event: KeyboardEvent) => {
 				this.dispose();
+				event.preventDefault();
 			}));
 		} else {
 			this.dispose();