mapbox / mapbox/supermercado

_feature_extrema() in burntiles.py does not handle multigeometry types

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Description

Hi,

I don't actually know much about this library but I had [a problem when using robosat](https://github.com/mapbox/robosat/issues/217) where multipolygons were causing a breakdown

I eventually tracked it down to [this function](https://github.com/mapbox/supermercado/blob/ecc9f5a36c1c8d13872df5bdcbd01621e5f3ab48/supermercado/burntiles.py#L29) in burntiles.py. A multipolygon causes it to crash out due to the case not being handled in the if/elif construct and there is no else statement.

Like I said I don't know much about this library so I don't know if it is possible to make this handle multigeometry types. If not then maybe it should throw a more descriptive error.

Cheers

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Research direction

Start in supermercado/burntiles.py at _feature_extrema() and trace how the multipolygon from the linked RoboSat report reaches that function. Check the existing geometry cases and establish whether multigeometries should be supported or rejected descriptively; done means the crash is addressed with behavior consistent with the library's intended scope.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
backend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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