ENH: verifying number of inputs in otbImageToPointSetFilter

Code/BasicFilters/otbImageToPointSetFilter.txx

@@ -87,6 +87,7 @@ const typename ImageToPointSetFilter<TInputImage,TOutputPointSet>::InputImageTyp
 ImageToPointSetFilter<TInputImage,TOutputPointSet>
 ::GetInput(unsigned int idx)
 {
+    
   return dynamic_cast<const InputImageType*>
     (this->ProcessObjectType::GetInput(idx));
 }
@@ -97,8 +98,11 @@ ImageToPointSetFilter<TInputImage,TOutputPointSet>
 template <class TInputImage, class TOutputPointSet>
 const typename ImageToPointSetFilter<TInputImage,TOutputPointSet>::InputImageType *
 ImageToPointSetFilter<TInputImage,TOutputPointSet>
-::GetInput()
+::GetInput(void)
 {
+  if(this->GetNumberOfInputs() < 1)
+    return 0;
+  
   return dynamic_cast<const InputImageType*>
     (this->ProcessObjectType::GetInput(0));
 }