Check for empty flash write when trying to write small items

[danheuck]

Closes #115

Also updated the mock flash to check that the data length is aligned and not equal to zero so that it will show up in tests.

[diondokter]

Thanks!

Could you add a line to the changelog?

I'll merge and release tomorrow.

[danheuck]

• Updated the changelog
• Updated the Item::read_item() function to avoid issuing zero-length reads as well. Should fix the fuzzing failure.

[diondokter]

Thanks!

(Though next time, add the line to the changelog under the unreleased section)

[diondokter]

Released as 7.0.1 :)

[danheuck]

(Though next time, add the line to the changelog under the unreleased section)

Woops, sorry, not sure what I was thinking.