Feature ClosePath command fails if only command in stream

[nicomgd]

I've been testing mapbox-gl-js with a custom dataset created using Mapbox Studio from a SHP file (world country boundaries, downloaded here in SHP).

While viewing the data, some tiles go missing and a console error appears :
Uncaught TypeError: Cannot read property 'push' of undefined.

The error happens with the current master build and with v0.7.0.

I've traced down the problem to VectorTileFeature.prototype.loadGeometry :

} else if (cmd === 7) {
    line.push(line[0].clone()); // closePolygon
}

This code expects line to be valid, but the data somehow has a feature which only contains a 7 command.

If I add a if (line) before line.push my data appears to be fine.

Is such data invalid ? or should mbgl-js be robust and handle this gracefully ?

[jfirebaugh]

Previously: #1019.

The data is invalid, due to a bug in mapnik-vector-tile that has been fixed, but not made it into a Mapbox Studio release yet. I've published a workaround to the library that gl-js uses and will integrate it into gl-js shortly.