add user_pcall variant that doesn't throw

[Byrth]

Tested using your example code and it no longer failed.

test1.lua:

print('test1 file')

a = 10

function file_unload()
    print(dummy.lol)
end

test2.lua:

print('test2 file')

b = 10

I toggle between the two using gs load test1 or gs load test2. Can check which file is loaded (or if both are somehow loaded) by toggling gs debugmode on and using gs eval print(user_env.a, user_env.b)

Before this patch, it fails to unload test1 and a always takes a value of 10. After the patch, it does successfully unload test1 and loads test2, so a goes to nil and b goes to 10. Swapping back and forth results in the expected changes.