Catch errors in updating the cache and report them to sentry (at least for the spreadsheets)

[kulla]

Sometimes in the update routine an error is raised (for example in updating the spreadsheet sometimes a timeout error occurs). Currently the update routine is written in a way, that in this case an empty spreadsheet is saved. This needs some investigation. Desired behavior:

• Do not change the cache in case of an error
• Report the error to sentry

The file https://github.com/serlo/api.serlo.org/blob/34d8f8b809b00abe6abf5b98b68b9d925bfce698/packages/server/src/internals/swr-queue.ts needs to be changed. See https://github.com/serlo/documentation/wiki/Cache on a documentation how the cache works.