InternalError when adding > 32768 callables

[qwenger]

import quickjs

c = quickjs.Context()
fcts = [c.add_callable(f"a{i}", lambda x: x) for i in range(32769)]
print(c.eval(f"a{len(fcts) - 2}(1)")) # passes
print(c.eval(f"a{len(fcts) - 1}(2)")) # InternalError

• Despite the JS_NewCFunctionMagic function accepting an int magic, only the range of int16_t is valid, see upstream bug report: https://www.freelists.org/post/quickjs-devel/int-magic
• Once that bug is fixed, raise a proper error message if outside the allowed range.