fix test

src/qglview_test/qglview_window.cpp

@@ -35,6 +35,7 @@ public:
 	void reloadShaders() { QGLEngineShaders::loadShadersMulti(mys, "test1.glsl"); }
 	void draw() {
 		if (!mys) return;
+		if (!mys->isLinked()) return;
 		auto planes = getFreePlanes(1);
 		bindPreviousOutput(0);
 		// bindDeferredBuffer(Renderer::dbrNormalZSolid, 1);