DPL: properly handle getting non-existing bindinds

The current code only works because the template specialization happens
late enough.

This might or might not be the case, depending for example if one decides to
force a given table's code out-of-line.

Framework/Core/include/Framework/ASoA.h

@@ -781,6 +781,11 @@ struct ColumnDataHolder {
   arrow::ChunkedArray* second;
 };
 
+template<typename T, typename B>
+concept HasBinding = requires(T& t) {
+    { t.B::mColumnIterator };
+};
+
 template <typename IP, typename... C>
 struct RowViewCore : public IP, C... {
  public:
@@ -964,7 +969,23 @@ struct RowViewCore : public IP, C... {
   template <typename DC, typename... B>
   auto bindDynamicColumn(framework::pack<B...>)
   {
-    DC::boundIterators = std::make_tuple(&(B::mColumnIterator)...);
+    DC::boundIterators = std::make_tuple(getDynamicBinding<B>()...);
+  }
+
+  // Sometimes dynamic columns are defined for tables in
+  // the hope that it will be joined / extended with another one which provides
+  // the full set of bindings. This is to avoid a compilation
+  // error if constructor for the table or any other thing involving a missing 
+  // binding is preinstanciated.
+  template <typename B>
+    requires (HasBinding<table_t, B>)
+  auto getDynamicBinding() {
+    return &B::mColumnIterator;
+  }
+
+  template <typename B>
+  auto getDynamicBinding() {
+    return nullptr;
   }
 };