Fix crash after uninstalling app

updateState was invoked in loader callback. But the
package was uninstalled at the callback time caused
null pointer exception. Add null check to prevent
null pointer access.

Fixes: 136170218
Fixes: 133771724
Test: make RunSettingsRoboTests, manual
Change-Id: I2715e77f6e32af42a4bce70c9f409b0311eb36c4
(cherry picked from commit 790a8225)