Possible to wedge logs DB if DB exists without object stores

[jryans]

If you happen to have an existing IndexedDB logs DB but without any object stores inside, then submitting logs will not work for you. (This edge case seems to have occurred on at least @lampholder's machine in the past.)

From looking at the code in rageshake.js, it looks like we open a connection to the logs DB, and then if it's first time we've ever done that, we'll create the object stores via onupgradeneeded.

However, it seems possible to load the app just long enough for the DB itself to be created, then close the tab / refresh / etc. so that the object stores are not created. Because we only create them via onupgradeneeded, we would never try again.

Perhaps we should do something safer here to test the DB structure after open and create object stores as needed based on that, especially since we'd like debug logs to work in as many strange and unexpected environments as possible.