Warning in Resharper "Return value of pure method is not used"

I have a quick question regarding a warning that I am getting from Resharper in Visual studio on a c# project that I am working. The warning is:

" Return Value of pure method is not used"

The method where this is happening is as below:

 private static bool FilePathHasInvalidChars(string userInputPath)
    {
        try
        {
            //this is where the warning occurs:
            Path.GetFullPath(userInputPath);

        }
        catch (Exception e)
        {
            Log.Error(String.Format(
                "The Program failed to run due to invalid characters or empty " + 
                "string value for the Input Directory. " + 
                "Full Path : <{0}>. Error Message : {1}.",
                userInputPath, e.Message), e);
            return true;

        }
        return false;
    }

I think I know why the warning is happening. I am using Path.GetFullPath(path) only for the purpose of catching all exceptions to do with invalid characters. The path is to be supplied as input by the user therefore I do not actually use the result of the Path.GetFullPath(userInputPath). The only use I have for it is on a check that I have for this method is on a check that I do on the main method to ensure the path supplied is not empty or does not have any invalid characters.

The place where I use the above method is as below:

if (FilePathHasInvalidChars(inputDirectory))
{
     return;
}

Basically it is just an exit point before program commences execution using an invalid parameter.

I was wondering if this warning would cause any issues or if I am misusing the Path.GetFullPath method in a way which will cause me problems in the future?