fix

app.py

@@ -90,7 +90,7 @@ def render_table(forms, lemmas, upos, xpos, feats, metadata, edges, edge_labels)
         ["<b>lemmas</b>          "] + lemmas,
         ["<b>upos</b>          "] + upos,
         ["<b>xpos</b>          "] + xpos,
-        ["<b>feats</b>          "] + feats[0],
+        ["<b>feats</b>          "] + list(feats[0]),
         *([""] + list(row) for row in feats[1:])
     ]