Positron style `boundary_3` filter logs runtime error when `admin_level` is `null`

[tordans]

Hi! We’re using the OpenFreeMap Positron style as our MapLibre basemap:

https://tiles.openfreemap.org/styles/positron

We consistently see this browser console error:

Expected value to be of type number, but found null instead.

Context

• Map client: MapLibre GL JS (via react-map-gl)
• Project (Alpha) https://github.com/osmberlin/osm-boundary-checker-germany

Suspected cause

The style layer boundary_3 appears to do numeric comparisons on admin_level:

• >= admin_level 3
• <= admin_level 6

Some features seem to have admin_level: null, which triggers the runtime expression type warning.

Expected behavior

No expression type errors in console when rendering the style.

Workaround on our side

We suppress the error by replacing the filter with a null-safe variant that first checks type:

• ['==', ['typeof', ['get', 'admin_level']], 'number']
• then the numeric comparisons.

Could the style be updated to guard admin_level before numeric comparisons in boundary_3?
Thanks!

[hyperknot]

Thanks @tordans, clear report and good diagnosis. The `typeof` guard is exactly the right fix. Would you be up for sending a PR to the styles repo? https://github.com/hyperknot/openfreemap-styles - ideally applied across all styles, not just Positron.

[tordans]

Happy to…

Would you be up for sending a PR to the styles repo?
https://github.com/hyperknot/openfreemap-styles - ideally applied
across all styles, not just Positron.

hyperknot/openfreemap-styles#18