### 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(!fd);
	MutexLock lock(fd->mutex);
	if (fd->antialiasing != p_antialiasing) {
		_font_clear_cache(fd);
		fd->antialiasing = p_antialiasing;
	}
}
TextServer::FontAntialiasing TextServerFallback::_font_get_antialiasing(const RID &p_font_rid) const {
	FontFallback *fd = font_owner.get_or_null(p_font_rid);
	ERR_FAIL_COND_V(!fd, TextServer::FONT_ANTIALIASING_NONE);
	MutexLock lock(fd->mutex);
	return fd->antialiasing;
}
void TextServerFallback::_font_set_generate_mipmaps(const RID &p_font_rid, bool p_generate_mipmaps) {
	FontFallback *fd = font_owner.get_or_null(p_font_rid);
	ERR_FAIL_COND(!fd);
	MutexLock lock(fd->mutex);
	if (fd->mipmaps != p_generate_mipmaps) {
		for (KeyValue<Vector2i, FontForSizeFallback *> &E : fd->cache) {
			for (int i = 0; i < E.value->textures.size(); i++) {
				E.value->textures.write[i].dirty = true;
				E.value->textures.write[i].texture = Ref<ImageTexture>();
			}
		}
		fd->mipmaps = p_generate_mipmaps;
	}
}
bool TextServerFallback::_font_get_generate_mipmaps(const RID &p_font_rid) const {