CachingAssetAccessor accidentally cache an invalidate response

[baothientran]

Report at https://github.com/CesiumGS/cesium-unreal-demo/issues/17

The accessor usually checks the status code to be a success response before caching it. However, it seems to be the status code is not enough to determine if the response is valid.

[argallegos]

Just wanted to note that this is still an issue, albeit a very rare one. Even reinstalling the plugin and UE does not seem to fix this, and it can result in no tilesets loading.

Seems to always come with the following error message: LogCesiumNative: Error: [2021-03-04 16:37:40.959] [error] [Tileset.cpp:464] Error when parsing tileset JSON, error code 3 at byte offset 0

To fix: While the UE editor is CLOSED, open Windows explorer to %userprofile%\AppData\Local\UnrealEngine\4.26. Delete the cesium-request-cache.sqlite file inside that directory.

[shehzan10]

While the UE editor is CLOSED, open Windows explorer to %userprofile%\AppData\Local\UnrealEngine\4.26. Delete the cesium-request-cache.sqlite file inside that directory.

As a workaround this might be ok temporarily. Should the proper solution be to add a frontend button to clear cache?

[argallegos]

User here reported an issue where suddenly no terrain loads and the project crashes on play. The error message they were receiving was:

LogCesium: Warning: [2022-03-16 10:31:31.523] [warning] [TileContentFactory.cpp:112] No loader registered for tile with content type ‘image/jpeg’ and magic value ‘???’.

The issue was resolved by deleting the sqlite cache as mentioned above.

This is the second report of an issue like this within the last two days, which is sort of a lot.

Frontend button would be more user-friendly, but I'm not sure if this can be fixed while the editor is open. Can we automatically detect this and refresh the cache somehow?