How to return error if flow of Power Automate didn't find value in the table(Excel)?

Hello,

I have the following problem: I set a variable via Power Virtual Agents that I want to find in a table in Excel, run the Power Automate, search for it and return it to Power Virtual Agents. But how can I display some message to the user if this variable was not found in the table? I tried to do it through the length of the returned variable, but it is not zero. Because of it, i'm getting only this error