Check if slice provider was initialized

If dagger fails to inject the object properly, it captures and logs
the exception but continues to start the slice provider as if
everything was fine. Check for this, log an error, and return false.

Test: manual - this is a rare injection issue
Flag: EXEMPT bugfix
Fixes: 376019842
Change-Id: I012e4ff52c3c9b75acf7b6f5138e7ed43267bf6a