Fix race condition with PIN char delete

This CL is an attempt to fix a race condition that exists but
one that I cannot find. Protect the code from crashing, and reset
the bouncer state if this happens.

Fixes: 395234761
Test: manual, attempt to race
Flag: EXEMPT bugfix
Change-Id: Ic0d251aa09ffcef9ac1b29632c4ed1917d655782