Raise more informative better errors, change some warnings to errors.

[bmschmidt]

User feedback.

I feel you should raise an error instead of only logging something if I’ve run out of storage. In prod I need to abort if I’ve hit the limit or I might end up serving a db with only half the points in. This also happens if I try to upload values which have conflicting ids. At the very least don’t log ‘Upload succeeded’ when it didn't

[bmschmidt]

Our details on failed uploads can be extremely uninformative, and should be improved. Example from discord

Shard upload failed: {"detail":"Upload failed"}
Additional info: {"detail":"Your project has only 0 datums. Please add at least 20 datums!"}

[ez2rok]

I received the same error
Additional info: {"detail":"Your project has only 0 datums. Please add at least 20 datums!"}
when accidentally including nan values in my data. We should raise a separate error if the data contains a nan value.

[iblind]

I've also encountered the same error as @ez2rok did (re: 20 datums) but the data I'm uploading contains several thousand data points. I'm not sure how this behavior emerges/where the error actually is, but I don't have any nan values in my dataset.