MapBox Studio fails to complain about "invalid" SVGs

[mryellow]

Steps to Trigger Behavior

1. Upload an SVG containing style or other "invalid" markup to MapBox Studio

Expected Behavior

1. Upload an SVG containing style or other "invalid" markup to MapBox Studio
2. Display an error informing the user that this image will not be usable
3. Observe the image not displaying within the MapBox Studio list

Actual Behavior

1. Upload an SVG containing style or other "invalid" markup to MapBox Studio
2. Observe no errors
3. Observe no problems displaying within MapBox Studio
4. Observe not included in https://api.mapbox.com/styles/v1/{username}/{styleid}

No indication is given that there may have been a problem with this upload, leading to wasted time debugging endpoints, re-punishing, clearing caches and the like before realising it's that the SVG isn't supported and no errors have been thrown to indicate this.