Simple task, write a program/function that returns error if and only if presented with itself.
The program must give a valid output for any input other than itself.
For the error part, you can only use errors already built in errors that comes with your language of choice. New/ self-defined error messages are not allowed.
The output should be of the same type as the input. (int, float, string, array, boolean, etc.) Except in the case if presented with itself of course.
Standard loopholes forbidden, lowest byte wins.