`rem` errors for arguments that don't fit into storage type

[matthias314]

MWE:

julia> @emulate Int3 UInt3

julia> 127 % Int3, 255 % UInt3
(-1, 0x7)

julia> 128 % Int3
ERROR: InexactError: trunc(Int8, 128)
[...]

julia> 256 % UInt3
ERROR: InexactError: trunc(UInt8, 256)
[...]

[PatrickHaecker]

Thanks for catching this, @matthias314! I changed the convert to using rem itself and the valid methods became faster skipping the test of whether they need to throw.