Catch invalid click exception

applications/gui/src/main.cpp

@@ -170,7 +170,15 @@ class FTLApplication : public nanogui::Screen {
 
 				float sx = ((float)p[0] - positionAfterOffset[0]) / mScale;
 				float sy = ((float)p[1] - positionAfterOffset[1]) / mScale;
-				Eigen::Vector4f camPos = src_->point(sx,sy);
+
+				Eigen::Vector4f camPos;
+
+				try {
+					camPos = src_->point(sx,sy);
+				} catch(...) {
+					return true;
+				}
+				
 				camPos *= -1.0f;
 				Eigen::Vector4f worldPos =  src_->getPose() * camPos;
 				lookPoint_ = Eigen::Vector3f(worldPos[0],worldPos[1],worldPos[2]);