Stop system process crash in TouchExplorer

We need to straighten out this state machine so we can
fix bugs in it without a high risk of creating others
(b/38246304). In the meantime, catching this exception at
least allows the device to keep operating.

Bug: 37338581
Test: Reproduced the conditions of the crash. Verified that
we now print the log message.

Change-Id: I1f4f84b5529b2bf638e225d474808e3d42484e78