How can I process the output of my synchronous loop one by one?

[pyrrho]

Short Answer: Functions in the workflow.

Longer Answer:

You should create the Get request (stripeInvoiceQuery) and the Email (sendEmail) as a function within your workflow and setup the parameters for each as needed. What is currently query2 should then loop as JS Code with something like:

try{
let response = await stripeInvoiceQuery(query1.data[index])
let followUpResponse = await sendEmail(query1.data[index], response.amount_paid)
return followUpResponse
}
catch (error) {
return error
}

This should then send the emails per iteration instead of looping around again at the end. Here's an even more in depth setup example for these functions and how you can try/catch and handle errors following the loop.

Loop block tells me to refer to {{ value }}, then says it's undefined

Does the loop run even and insert records even though the linter is claiming that value is undefined? Sometimes the linter is tricksy. I notice that you are using the legacy loop block to execute some nested looping (which I have had to do in the past). I recommend trying to shift into the paradigm of creating functions for your workflows which you can then call from a JS setup in the new loop blocks. This way you can gather results from the loop iterations with a try/catch block to format the…