videonode: Do not finish if material is different

Fix bluerobotics/qgroundcontrol#164
Signed-off-by: Patrick J.P <patrickelectric@gmail.com>

src/VideoStreaming/gstqtvideosink/painters/videonode.cpp

@@ -52,14 +52,18 @@ void VideoNode::setMaterialTypeSolidBlack()
 
 void VideoNode::setCurrentFrame(GstBuffer* buffer)
 {
-    Q_ASSERT (m_materialType == MaterialTypeVideo);
+    if (m_materialType != MaterialTypeVideo) {
+        return;
+    }
     static_cast<VideoMaterial*>(material())->setCurrentFrame(buffer);
     markDirty(DirtyMaterial);
 }
 
 void VideoNode::updateColors(int brightness, int contrast, int hue, int saturation)
 {
-    Q_ASSERT (m_materialType == MaterialTypeVideo);
+    if (m_materialType != MaterialTypeVideo) {
+        return;
+    }
     static_cast<VideoMaterial*>(material())->updateColors(brightness, contrast, hue, saturation);
     markDirty(DirtyMaterial);
 }