Dependency: error 500 is thrown when rejecting a Dependency to a Program without Committed Date

Issue Summary

When a Dependency that depends on a Program is rejected, if the Committed By by is not set (at the moment of entering the "No Work / Rejected Reason:"), a Server.500 error is thrown.

Steps to Reproduce

1. Create a Dependency from a Program/Agile Team, to a Program
2. Set a Sprint as Needed By
3. When everything is done, click on the Reject Button.
4. Now fill in the "No Work / Rejected Reason:" and try to save (leave the "Committed By" blank)

Expected Results

No errors would appear

Actual Results

A Server 500 is thrown

Workaround

Fill the "Committed By" with a Sprint, before entering the "No Work / Rejected Reason:" and saving.