Merge "Return error instead of unloading existing model" into nyc-dev am: c57616f
am: f012135

* commit 'f0121355eb5b6942945b49a8c4df5db6195e3ee9':
  Return error instead of unloading existing model

Change-Id: I4bdad416b6c3682c7f62721b59482f4422b2b265