Do not attempt to render uninstantiated fields

Review Request #7787 — Created Dec. 1, 2015 and submitted — Latest diff uploaded

Information

Review Board
release-2.5.x
04ba860...

Reviewers

Previously, an error in instantiating a ReviewRequestField would
lead to an error being logged, but the field would still be attempted to
be rendered. Since the instantiation failed, the variable would be
uninitialized leading to an UnboundLocalError.

Now, if the field cannot be insantiated, we skip to the next field in
the fieldset.

Ran unit tests.