Fix for #789 : NativeCallback unable to leave thread's last error unchanged
Though JavaScript function wrapped as a NativeCallback allows both inspecting and altering the current thread's system error, it wasn't possible to leave the system error as-is. Unless replaced by a value unequal to the original, the system error was being forced to 0 upon return from the NativeCallback. Fixed and tests added.
Fix for #789 : NativeCallback unable to leave thread's last error unchanged
Though JavaScript function wrapped as a NativeCallback allows both inspecting and altering the current thread's system error, it wasn't possible to leave the system error as-is. Unless replaced by a value unequal to the original, the system error was being forced to 0 upon return from the NativeCallback. Fixed and tests added.