RCv3 gathering malformed body

[manishtomar]

Have seen below exception few times probably because RCv3 response is malformed. This is not really an issue as convergence retry next time fixes it but would be nice to have better error handling instead of spitting out exception stacktrace.

File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/_base.py", line 146, in _run_callbacks
    result = guard(cb, value)
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/_base.py", line 78, in guard
    return (False, f(*args, **kwargs))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/do.py", line 121, in <lambda>
    error=lambda e: _do(e, generator, True))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/do.py", line 98, in _do
    val = generator.throw(*result)
--- <exception caught here> ---
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/otter/convergence/service.py", line 577, in converge_one_group
    result = yield non_concurrently(currently_converging, group_id, cvg)
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/_base.py", line 78, in guard
    return (False, f(*args, **kwargs))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/do.py", line 120, in <lambda>
    return val.on(success=lambda r: _do(r, generator, False),
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/do.py", line 100, in _do
    val = generator.send(result)
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/otter/convergence/service.py", line 507, in non_concurrently
    result = yield eff
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/_base.py", line 78, in guard
    return (False, f(*args, **kwargs))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/otter/convergence/service.py", line 543, in <lambda>
    error=lambda e: after_eff.on(lambda _: six.reraise(*e)))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/_base.py", line 78, in guard
    return (False, f(*args, **kwargs))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/do.py", line 121, in <lambda>
    error=lambda e: _do(e, generator, True))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/do.py", line 98, in _do
    val = generator.throw(*result)
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/otter/convergence/service.py", line 301, in execute_convergence
    get_executor=get_executor))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/_base.py", line 78, in guard
    return (False, f(*args, **kwargs))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/do.py", line 121, in <lambda>
    error=lambda e: _do(e, generator, True))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/do.py", line 98, in _do
    val = generator.throw(*result)
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/otter/convergence/service.py", line 253, in convergence_exec_data
    resources = yield executor.gather(tenant_id, group_id, now)
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/_base.py", line 78, in guard
    return (False, f(*args, **kwargs))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/_base.py", line 181, in catcher
    six.reraise(*exc_info)
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/effect/_base.py", line 78, in guard
    return (False, f(*args, **kwargs))
  File "/opt/otter/.ve/local/lib/python2.7/site-packages/otter/convergence/gathering.py", line 243, in on_listing_nodes
    for node in body
effect._intents.FirstError: (index=2) FirstError: (index=5) TypeError: 'NoneType' object is not iterable