Login to your appengine admin page and look for "Logs" link in the
left side.
Clicking it will show you the different types of logs and default logs
are "Error" related.
Click on the plus-es to see the description of the server logs. They
would let us understand where exactly our code
gone crazy or did not check for import dependencies. Remove unwanted
lines which are shown in the logs like
..blah blah on line number : #
In our code files.
Redeploy and run, make sure that the application is working, and then
rethink why did you put those lines and try to keep different versions
for development and production use.