race condition in terminal.dispose

[jerch]

Repro:

• open demo in browser
• call term.dispose()

The culprit seems to be the disposal of the webgl addon:

xterm.js/addons/addon-webgl/src/WebglAddon.ts

Lines 90 to 94 in 9186c72

	this._register(toDisposable(() => {
	const renderService: IRenderService = (this._terminal as any)._core._renderService;
	renderService.setRenderer((this._terminal as any)._core._createRenderer());
	renderService.handleResize(terminal.cols, terminal.rows);
	}));

Those lines recreate & attach a DOM renderer instance, which fails, if we are in the middle of terminal disposal. Imho it can be fixed by:

this._register(toDisposable(() => {
  if ((this._terminal as any)._core._store._isDisposed) {
    return;
  }
  const renderService: IRenderService = (this._terminal as any)._core._renderService;
  renderService.setRenderer((this._terminal as any)._core._createRenderer());
  renderService.handleResize(terminal.cols, terminal.rows);
}));