Surisingly, the compiler may detect the remaining obj_type in
the default switch. Then, inlining nmp_class_from_type() it may detect
that this is only possible to hit with an out or range access to
_nmp_classes array.
Rework the code to avoid that compiler warning. It's either way not
supposed to happen.
Also, drop the default switch case and explicitly list the enum values.
Otherwise it is error prone to forget a switch case.
(cherry picked from commit 9848589fbf)
(cherry picked from commit 6f189da7b6)
6da20c24cd