Improve error message if top.name is None

/close #196

tasks.py

@@ -496,13 +496,20 @@ def parse_protocol_async_inner(protocol):
 
     # TOPs
     old_tops = list(protocol.tops)
-    for top in old_tops:
-        protocol.tops.remove(top)
+    tops = []
     for index, fork in enumerate(
             (child for child in tree.children if isinstance(child, Fork))):
         top = TOP(
             protocol_id=protocol.id, name=fork.name, number=index,
             planned=False)
+        if top.name is None:
+            return _make_error(
+                protocol, "Parsing", "TOP-Name fehlt",
+                "'{Name' sollte '{TOP Name' lauten.")
+        tops.append(top)
+    for top in old_tops:
+        protocol.tops.remove(top)
+    for top in tops:
         db.session.add(top)
     db.session.commit()