Task splitting algorithm fails to split tasks when custom data extracts uploaded

[manjitapandey]

Describe the bug
Task splitting algorithm fails to split tasks. The API shows 200 but response shows null in the features. This can be reproduced by choosing custom data extracts.

To Reproduce
Steps to reproduce the behavior:

1. Go to create project
2. Click on Upload custom data extracts
3. select Task splitting algorithm
4. See error

Expected behavior
Smooth task splitting and project creation

Screenshots

[manjitapandey]

Related: #1172

[spwoodcock]

I think this is probably a frontend issue too - the custom data extract is not passing to either task splitting or the generate endpoints.

[ivangayton]

I'm about to start a brand-new dive into the splitting algorithm starting Monday. I suspect that in at least some situations, there are non-replicable failures. The splitting algorithm can probably fail given some kinds of broken OSM data, which wouldn't be replicable unless you tried to split exactly the same AOI with exactly the same parameters.

Basically I think we need:

• Me to provide better failure handling in the SQL
• Front end to provide more information about what happened when failures occur in the splitter
• Unit tests using data that's known to work so that if it breaks for some other reason we can quickly detect that

[spwoodcock]

We have point 3 covered - I wrote quite a few tests for fmtm-splitter 😄

You can run them with:

docker compose run --rm splitter pytest

With this in mind, I just wrote a very quick guide to testing updates to fmtm-splitter visually: https://hotosm.github.io/fmtm-splitter/testing-visually/
Hopefully it helps debugging @ivangayton

Also related hotosm/fmtm-splitter#24