BUG: Timestamp+int should raise NullFrequencyError, not ValueError
Last prerequisite before we can fix #28080.
What would a release note for this look like? IIUC, this is backwards compatible since catching a ValueError will still catch this NullFrequencyError? But we should still have a note describing the change so that users could tighten up the caught exception if they desire. > What would a release note for this look like?

This is a good question.  I'm hesitant to advertise the change because before long we'll be enforcing the deprecation, at which point this should raise TypeError. I think OK to just say something like `... now raises a NullFrequencyError` without worrying too much about the details of a future deprecation lgtm. maybe rebase and push again (as the CI is hanging) rebased+green Looks like some merge conflicts - can you fix up and repush? rebased+green thanks @jbrockmendel 