fixed the case where a trial has no category

src/graph_helpers.py

@@ -41,7 +41,11 @@ def simplify_text_description_nodes(G,node_index_dict,mode="None",min_freq=1):
     # we iterate over all trials
     for i,tn in enumerate(trialnodes):
         #get corresponding cat node
-        catn = [n for n in G.neighbors(tn[0]) if isinstance(G.nodes[n]["nodeobj"],dh.OffenceNode)][0]
+        catn = [n for n in G.neighbors(tn[0]) if isinstance(G.nodes[n]["nodeobj"],dh.OffenceNode)]
+        if not catn:
+            continue
+        else:
+            catn=catn[0]
         catn=[catn,G.nodes[catn]]
         category=catn[1]["nodeobj"].d["category"]
         descr_vectors = None