Fix Producer clone implementation check.

include/aidge/operator/Producer.hpp

@@ -67,10 +67,10 @@ public:
         for (std::size_t i = 0; i < static_cast<std::size_t>(nbOutputs()); ++i) {
             mOutputs[i] = std::make_shared<Tensor>(*(op.getOutput(i)));
         }
-        if (op.mImpl){
-            SET_IMPL_MACRO(Producer_Op, *this, op.mOutputs[0]->getImpl()->backend());
+        if (mOutputs[0]->getImpl() && Registrar<Producer_Op>::exists({mOutputs[0]->getImpl()->backend()})){
+            SET_IMPL_MACRO(Producer_Op, *this, mOutputs[0]->getImpl()->backend());
         }else{
-            mImpl = nullptr;
+            mImpl = std::make_shared<OperatorImpl>(*this);
         }
     }