Wrap reparent in a try-catch.

Apparently checking for validity is not enough, as there can be a
race condition that results in the leash being released between the
check and the reparent call. Wrapping in a try-catch and logging the
error instead to avoid crashing.

Fix: 404507270
Flag: EXEMPT bugfix
Test: manual
Change-Id: Ie5b0787ff6cb0262b03e43224e5652173f71b401