Create error tests for functions that use storage.Client

[calvinmclean]

I realized that I can force storage client errors in tests by using a &storage.Client{} without the initializer. I just need to update functions to check that c.db != nil and return error instead of panic.

Then, I can go and re-add tests that get coverage on storage client errors at least in the cases where there is not multiple storage client calls in a row.