[SofaQtQuickGUI] fix crash
[SofaQtQuickGUI] fix crash


Former-commit-id: 7934b635858c8f9ad2a7f42c502031999e2eb7d3
hdeling/sofa,hdeling/sofa,hdeling/sofa,Anatoscope/sofa,Anatoscope/sofa,Anatoscope/sofa,FabienPean/sofa,FabienPean/sofa,FabienPean/sofa,FabienPean/sofa,Anatoscope/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,hdeling/sofa,hdeling/sofa,hdeling/sofa,hdeling/sofa,FabienPean/sofa,Anatoscope/sofa,FabienPean/sofa,hdeling/sofa,hdeling/sofa,Anatoscope/sofa,FabienPean/sofa,Anatoscope/sofa,Anatoscope/sofa,FabienPean/sofa,FabienPean/sofa