### Godot version

4.0 dev Beta 10

### System information

MacBook Pro M1 Max

### Issue description

After I imported font.ttf file and move it from one folder to another under ://res godot suddenly crashed, and it still crashes after restart.

### Steps to reproduce

Import some font.ttf file and try to move into different folder

### Minimal reproduction project

N/A
FontFallback *fd = font_owner.get_or_null(p_font_rid);
	ERR_FAIL_COND_V(!fd, PackedInt32Array());
	MutexLock lock(fd->mutex);
	Vector2i size = _get_size_outline(fd, p_size);
	ERR_FAIL_COND_V(!_ensure_cache_for_size(fd, size), PackedInt32Array());
	PackedInt32Array ret;
	const HashMap<int32_t, FontGlyph> &gl = fd->cache[size]->glyph_map;
	for (const KeyValue<int32_t, FontGlyph> &E : gl) {
		ret.push_back(E.key);
	}
	return ret;
}
void TextServerFallback::_font_clear_glyphs(const RID &p_font_rid, const Vector2i &p_size) {
	FontFallback *fd = font_owner.get_or_null(p_font_rid);
	ERR_FAIL_COND(!fd);
	MutexLock lock(fd->mutex);
	Vector2i size = _get_size_outline(fd, p_size);
	ERR_FAIL_COND(!_ensure_cache_for_size(fd, size));
	fd->cache[size]->glyph_map.clear();
}
void TextServerFallback::_font_remove_glyph(const RID &p_font_rid, const Vector2i &p_size, int64_t p_glyph) {
	FontFallback *fd = font_owner.get_or_null(p_font_rid);
	ERR_FAIL_COND(!fd);
	MutexLock lock(fd->mutex);
	Vector2i size = _get_size_outline(fd, p_size);
	ERR_FAIL_COND(!_ensure_cache_for_size(fd, size));
	fd->cache[size]->glyph_map.erase(p_glyph);
}
Vector2 TextServerFallback::_font_get_glyph_advance(const RID &p_font_rid, int64_t p_size, int64_t p_glyph) const {