You have to write a program, if its source code is reversed, then it will error.
For example, if your source is
ABC, then reversing it and writing
CBA should crash/throw an error. And
ABC itself should be a vaild program (I mean your primary source should be a valid program). Output of the main source code can be empty, but your
ABC code I mean primary source should not output anything to standard error.
Also the minimum length of a solution is 2 bytes.
Standard loopholes apply, shortest code wins.