Provide more info for the TypeError

[AlexMost]

This error looks a little bit cryptic:

  File "/work/uaprom/site/controllers/graphql.py", line 81, in graphql
    graph_result = execute_graph(query, ctx)
  File "/work/uaprom/site/controllers/graphql.py", line 48, in execute_graph
    result = hiku_engine.execute(GRAPH, query, ctx=ctx)
  File "/usr/local/lib/python2.7/dist-packages/hiku/engine.py", line 285, in execute
    return self.executor.process(queue, q)
  File "/usr/local/lib/python2.7/dist-packages/hiku/executors/sync.py", line 17, in process
    queue.progress(queue.__futures__)
  File "/usr/local/lib/python2.7/dist-packages/hiku/executors/queue.py", line 38, in progress
    callback()
  File "/usr/local/lib/python2.7/dist-packages/hiku/engine.py", line 198, in <lambda>
    _fut.result())
  File "/usr/local/lib/python2.7/dist-packages/hiku/engine.py", line 59, in store_fields
    result.root.update(zip(names, query_result))
TypeError: zip argument #2 must support iteration

It would be great to have more useful information in this case.