[Fix] Catch Exception for Adding Structures / Show PubChem Substances (#168)

Fixes #163
Fixes #165

Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#168

epdb/views.py

@@ -1251,7 +1251,16 @@ def package_compound_structures(request, package_uuid, compound_uuid):
         structure_smiles = request.POST.get("structure-smiles")
         structure_description = request.POST.get("structure-description")
 
-        cs = current_compound.add_structure(structure_smiles, structure_name, structure_description)
+        try:
+            cs = current_compound.add_structure(
+                structure_smiles, structure_name, structure_description
+            )
+        except ValueError:
+            return error(
+                request,
+                "Adding structure failed!",
+                "The structure could not be added as normalized structures don't match!",
+            )
 
         return redirect(cs.url)