Are you sure this is a regression?

I am getting following assert in Debug builds:

BLI_assert failed: source/blender/blenlib/intern/math_rotation.c:1589, get_rotation_order_info(), at 'order >= 0 && order <= 6'

But no crash in Release builds

Well it is always good to have an eye on asserts [after all, they tell you something is not working as expected]
In this case I am not so sure if it is worth chasing this more... Keyframing enums is special, not sure how we'd safeguard properly here.

Still, letting @Sybren A. Stüvel (sybren) know

P.S.: you can disable "crash" on asserts in Debug builds with this CMAKE option WITH_ASSERT_ABORT

In T82669#1053887, @Christoph Lendenfeld (ChrisLend) wrote:

Sorry I missed that. I didn't know asserts would cause a crash in debug builds.
In that case I will close that issue then.

The assertion failing shows that there is a problem, in that the data fed to a function doesn't adhere to the expected range, so the function will not do the right thing. We shouldn't be accepting a failing assert in the same way that we don't accept a failing unit test.

We could keep this report open as a Known Issue, or as a low-priority bug. Not sure how hard it would be to find a proper fix for this, though.