Don't crash when serving NoSuchReview error
Add TC for "Don't crash when serving NoSuchReview error"
Don't crash when trying to delete filter that doesn't exist

The error can be repro'd by using "Add Filter" in a review,
then keeping it open in 2 tabs and deleting the added filter
in both tabs.
Add TC for "Don't crash when trying to delete filter that doesn't exist"
Raise an error if invalid user IDs are passed to /addreviewfilters operation
Add TC for "Raise an error if invalid user IDs are passed to /addreviewfilters operation"