Don't throw error when repo can't be find
Don't throw error when repo can't be find

When visiting page of repo that doesn't exist, we should not throw an
error. It still does not work as expected, redirecting to
/undefined/undefined, which should be addressed as well, but at least we
don't throw errors now.

mjlambert/travis-web,mjlambert/travis-web,fauxton/travis-web,jlrigau/travis-web,fauxton/travis-web,travis-ci/travis-web,fauxton/travis-web,Tiger66639/travis-web,mjlambert/travis-web,2947721120/travis-web,travis-ci/travis-web,fotinakis/travis-web,jlrigau/travis-web,jlrigau/travis-web,2947721120/travis-web,2947721120/travis-web,fotinakis/travis-web,fauxton/travis-web,fotinakis/travis-web,Tiger66639/travis-web,mjlambert/travis-web,fotinakis/travis-web,Tiger66639/travis-web,Tiger66639/travis-web,travis-ci/travis-web,travis-ci/travis-web,jlrigau/travis-web,2947721120/travis-web