It is not possible to get person information in the localtest environment

## Description
When we have to lookup person information (from DSF) dynamically based on a person number, its required that we add code in the backend in processwrite to get the person information and fill it for the user. But this throws error

## To Reproduce
1. Go to 'ProcessDataWrite' in DataProcessingHandler
2. Add code to fill person information fields based on person number input field
3. Run the application, navigate to the person number input field, type in the person number and move out of the field
4. Unknown error

## Expected behavior
Person information is retreived and filled in the mapped input fields

## Screenshots

Start at ProcessDataWrite in DataProcessingHandler and reproduce the person-number lookup in the localtest environment using the steps in the issue. Trace the unknown error when leaving the person number field; done means person information is retrieved and filled into the mapped input fields.

Written by the indexing model from the issue text.