[Bug] UTF-8 unicode characters break editor.setSelection()

Reproducible in vscode.dev or in VS Code Desktop?

• Not reproducible in vscode.dev or VS Code Desktop

Reproducible in the monaco editor playground?

• Not reproducible in the monaco editor playground

Monaco Editor Playground Link

https://microsoft.github.io/monaco-editor/playground.html?source=v0.52.2#XQAAAAK4AQAAAAAAAABBqQkHQ5NjdMjwa-jY7SIQ9S7DNlzs5W-mwj0fe1ZCDRFc9ws9XQE0SJE1jc2VKxhaLFIw9vEWSxW3yscwz4UdefGetpg8d5BCIdogK6CBmgyKHIOVjH6uO-oA-RA-rcpQdGBlgwMT7NDeGjyzFyz9GIFhxIjM8PaJX1w-Sn1-zVqI7zlVTjeD18bmPsOVFVefc6MrYvRcdx8l9iq4V0F3JMDQgtBbzmMZkEH22NulEWVlzmUtaVkcBElTZESeMyaeKnZ2-M_HGJvBB5rL3oO4vMoBYbM4blj_ehEz2ZUN5kD2uurNuhC5NWAEYhu-5G_mmeZVyZrzG6Bp9DAMm9lS6uO5atSkev8y42pflCpbZA4oHbY3PIbQR2Wauxd3muQd_AC3iU98YHPcvKtWqfBbKLDuLXKUhfc0azydlIUE6fyGSGU

Monaco Editor Playground Code

const value = /* set from `myEditor.getModel()`: */ `var 💣 2`;

// Hover on each property to see its docs!
const myEditor = monaco.editor.create(document.getElementById("container"), {
	value,
	automaticLayout: true,
});

myEditor.setSelection({
	endColumn: 6,
	endLineNumber: 1,
	startColumn: 5,
	startLineNumber: 1
})

console.log("DEBUG: " + myEditor.getSelection())

Reproduction Steps

After code executes, watch the editor current selection as well as the console log.

Actual (Problematic) Behavior

The unicode character doesn't get selected, also, the editor.getSelection() value doesn't match the one I put in in the previous editor.setSelection() call.

Expected Behavior

I expect to see the bomb emoji as selected, also notice what value gets retrieved when i call editor.getSelection() afterward (i logged the value in the console).

Additional Context

If you change the setSelection values to 1:1 -> 1:2 the selection works, but if you put 1:7 -> 1:8 it selects the wrong character (supposed to be the number)

Start by running the linked Monaco Editor Playground example with var 💣 2 and compare setSelection() with the subsequent getSelection() result. Trace the editor selection and column-handling entry points involved; done means the emoji is selected for columns 5–6 and the returned selection matches the requested range.