REPL: the "undo" keyboard shortcut may replace all the content in a file with content from another tab

[li6in9muyou]

reproduce

1. go to https://svelte.dev/repl/6207fed523fa45038e285262cacee9e9
2. you are at App.svelte initially and neither of the two tabs has star sign in it
3. change to the a.js tab, which has "important stuff" in it
4. press the keyboard shortcut for "undo" e.g. ctrl+z on windows

actual behaviour

Important stuff in a.js is gone, replaced by content of App.svelte. The "redo" shortcut will restore important stuff.

expected behaviour

The "undo" keyboard shortcut does nothing at step 4.

possible fix

Add entries to intercept the "undo" and "redo" commands in codemirror editor options, see below.

sites/packages/repl/src/lib/CodeMirror.svelte

Lines 167 to 196 in a7f6683

	const opts = {
	lineNumbers,
	lineWrapping: true,
	indentWithTabs: true,
	indentUnit: 2,
	tabSize: 2,
	value: '',
	mode: modes[mode] || {
	name: mode
	},
	readOnly: readonly,
	autoCloseBrackets: true,
	autoCloseTags: true,
	extraKeys: CodeMirror.normalizeKeyMap({
	Enter: 'newlineAndIndentContinueMarkdownList',
	'Ctrl-/': 'toggleComment',
	'Cmd-/': 'toggleComment',
	'Ctrl-Q': function (cm) {
	cm.foldCode(cm.getCursor());
	},
	'Cmd-Q': function (cm) {
	cm.foldCode(cm.getCursor());
	},
	// allow escaping the CodeMirror with Esc Tab
	'Esc Tab': false
	}),
	foldGutter: true,
	gutters: ['CodeMirror-linenumbers', 'CodeMirror-foldgutter'],
	theme
	};