prevent nullptr dereference when calling unwanted

When the EthernetNetworkAgent has already been stopped, a call to
unwanted will cause a crash due to a nullptr derefernce.

Bug: 197279734
Test: atest EthernetNetworkFactoryTest
Change-Id: Ice39c603bdd3e3139aa8ece7fb897bf7b567e74b
1 file changed
tree: 461805f84ed91e11dd817acd4ed40dbeb221446a
  1. service-t/
  2. tests/