Fix null value of additional entity when no additional entities are uploaded

[Sujanadh]

What type of PR is this? (check all applicable)

• 🍕 Feature
• 🐛 Bug Fix
• 📝 Documentation
• 🧑‍💻 Refactor
• ✅ Test
• 🤖 Build or CI
• ❓ Other (please specify)

Related Issue

• Issue: Small issues with form questions on mandatory XLSForm fields #1897

Describe this PR

This PR fixes the parsing of null value of additional entities as a string in form-data when no additional entities are uploaded. It updates the body of generate-project-data by parsing null as a JSON instead of form data.

Screenshots

N/A

Alternative Approaches Considered

Did you attempt any other approaches that are not documented in code?

Review Guide

Notes for the reviewer. How to test this change?

Checklist before requesting a review

• 📖 Read the FMTM Contributing Guide: https://github.com/hotosm/fmtm/blob/main/CONTRIBUTING.md
• 📖 Read the HOT Code of Conduct: https://docs.hotosm.org/code-of-conduct
• 👷‍♀️ Create small PRs. In most cases, this will be possible.
• ✅ Provide tests for your changes.
• 📝 Use descriptive commit messages.
• 📗 Update any related documentation and include any relevant screenshots.

[optional] What gif best describes this PR or how it makes you feel?

[spwoodcock]

This may need to be solved on the backend instead, where we check for null and do not process the additional entities if so

[spwoodcock]

Well done finding the problem!
It makes sense now 😄

But here I think form data was used to provide a file name, so that can give a name to the additional entity list.

Does this work correctly when using a json upload?

[Sujanadh]

Yes, this works correctly. 🎉

[Sujanadh]

The form data was used because of custom xlsform upload, we don't need form data only for the additional_entities list.

[spwoodcock]

But equally if this is working well, then we can keep this approach too! Just wanted to check