The delete and delete all are conveniently placed alongside each other and their warning messages are very similar making them easy to confuse.
I was thinking make a possible safety procedure regarding the Delete All button would be to hide it in a toggle.
The toggle would add an additional level of caution/distinction which would quite likely remove the chance of using it by accident.
My thinking would be that the that there would be a toggle 'delete all' button listed, when selected the content slides left and the real delete all button comes into view while the toggle button would be replaced with an X.

