In dashboard/dispatcher.py, create the WSGIApplication with debug=False.
In dashboard/dispatcher.py, create the WSGIApplication with debug=False.

In https://cloud.google.com/appengine/docs/python/tools/webapp/wsgiapplicationclass, it suggests always using debug=False; the difference is that when an exception is raised, in non-debug mode, it will still be logged, but an opaque "500 error" message is shown to the user instead of a call stack.

Review URL: https://codereview.chromium.org/1462423002

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