Remove unused variable assignments

exceptions/generic/MDInvalidEmail.php

@@ -13,8 +13,7 @@ final class MDInvalidEmail extends MDgenericInvalidInputsException {
      */
     public function errorMessage() {
         //error message
-        $errorMsg = 'Input URL is invalid';
-        return $errorMsg;
+        return 'Input URL is invalid';
 
     }
 }