HTMLSerializeHandler does not work: Cannot read properties of undefined (reading 'colors')

[connor4312]

1. Call serializeAddon.serializeAsHTML()
2. Observe the error Cannot read properties of undefined (reading 'colors'): TypeError: Cannot read properties of undefined (reading 'colors')

This seems to come from here, where _core appears to be a CoreTerminal which doesn't have a theme service.

xterm.js/addons/xterm-addon-serialize/src/SerializeAddon.ts

Lines 548 to 549 in ac923e5

	// https://github.com/xtermjs/xterm.js/issues/3601
	this._colors = (_terminal as any)._core._themeService.colors;

[connor4312]

I had to open xterm in an element first for the themeService to be created.

[Tyriar]

At the very least we should add an exception with a good error when you call before open

[silamon]

I think this is more or less the same as #4148, which can be solved by reviewing #4348.

[Tyriar]

@silamon yes it is indeed, thanks