Error Executing Workflow On User Input script

Error Executing Workflow On User Input script

so i get this message when trying to convert from native price to euro in lookup to single field

-  Error Executing Workflow On User Input script Price (Euro).
   -  Error occurred while executing the workflow. please contact support@zohocreator.com

failing code:
  2. euprice  =  Price_Native_currency1  [ID == input.Price_Native_currency];
  3. if (euprice != null)
  4. {
  5. EuValue = (euprice.Price_Native_currency.toLong()  *  0.10836).round(1);
  6. input.Price_Euro = EuValue.toString();
  7. }

And if im not doing "if" 
then im getting this error

Error in executing On User Input script of Price (Euro).
 Error.
   Error in executing Set Variable task. Unable to update template variable EuValue.
     Error evaluating NUMERIC expression :
       Error evaluating NUMERIC expression :
          Error evaluating NUMERIC expression :

failing code: 
i guess it needs a if statement somewhere but cant figure where and how.
  2. euprice  =  Price_Native_currency1  [ID == input.Price_Native_currency];
  3. EuValue = (euprice.Price_Native_currency.toLong()  *  0.10836).round(1);
  4. input.Price_Euro = EuValue.toString();