When attempting to rotate boxes in mesh files by values that should be accepted (like 90 or 67.5), it will not work.

Rotating it on the y axis by 90 will result in switching to the default resource pack with this error:

com.google.gson.JsonParseException: Invalid y rotation angle, expected one of [0, 22.5, -22.5, 45, -45] and got 90.0

This happens with any axis, and also can result in crashing Minecraft. Having no rotation (0 degrees) for every axis can also cause a crash (when it should just ignore the rotation request).

EDIT: This happened to me while trying to rotate a box inside in the lever mesh file.
Rotation of 90 degrees does work when inheriting meshes.