Vala double free bug

bugdemo.vala

Bytes get_bytes() {
	return new Bytes({0,1,2,3});
}

void double_free() {
	string vtxshader = (string)get_bytes();
	string frgshader = (string)get_bytes();
}

public static int main (string[] args) {
	double_free();
	return 0;
}