This one's simple. Grab some bombs (I always got them from enemy drops if it matters), and the counter for bombs will go to "A". However, you still functionally only have 4 bombs, but even after you run out, the counter will remain at "A" even though you lose the ability to use bombs as they disappear from the subscreen as per normal. This happens in 1st.qst and a custom quest I tested it in. This might be related to the bug about the key quantities from a few builds back, but I figure that it's different enough to merit its own thread (keys work completely fine in b288 as far as I can tell).
Bomb counter displays infinite(b288)
Haha, that's an unorthodox way to be making an unneeded bug report, though I can't complain about the final result.