Fixed a printer crash caused by empty parameter modifiers

[Andarist]

fixes crash reported here: #60527 (comment)

[typescript-bot]

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[Andarist]

The crash was caused by getPos rying to read .__pos that is meant to be added by onBeforeEmitNodeArray (called by emitDecoratorsAndModifiers, called by emitParameter). But since this list was empty it just bailed on it:

TypeScript/src/compiler/emitter.ts

Lines 4435 to 4436 in b3c67d3

	function emitDecoratorsAndModifiers(node: Node, modifiers: NodeArray<ModifierLike> | undefined, allowDecorators: boolean) {
	if (modifiers?.length) {

This fix tries to reuse existing p.modifiers (it feels like ensureParameter shouldn't try to los information). Since the parameters in question don't have any modifiers an undefined gets "reused". So then the printer doesn't crash on lacking .__pos because it doesn't even have see the related node array as it wasn't created in the first place.

This, of course, means that this can still crash, in a similar way, on empty modifiers if they are ever returned.

I think it would be best to keep the current fix (it avoids allocating a redundant empty array) but also call onBeforeEmitNodeArray on empty modifiers in emitDecoratorsAndModifiers. I glanced through the whole emitter.ts and it seems like it's the only function that avoids it. Do you think there is some extra test case to be written that would prove it needs to be done there?

This, of course, means that any similar