How to avoid this error?

[NelsonE]

Hi to all,
I'm using Pabbly Connect to access Google Sheet, lookup rows and do calculations, namely look for a row with a specific email address and calculate the difference between the current value and the previous one. The issue is when there is only the first value for the specific email address, in this case, I get an error.

How can I use Pabbly to do the calculation only when there is a previous value to compare with?
You can see in the image below what is being done in the math operation, which returns an error when "response result 0 row value" doesn't exist yet.

 

[Pabblymember11]

Hey @NelsonE

We looked into your workflow and it seems like for some email addresses there is only one value and because of that, the number formatter is unable to subtract because there is one value coming from Google Sheets.

Though you can use a filter action step to only process the values when there are two values to subtract.

 

[NelsonE]

Thank you @Supreme for your help. Just impleted it