Fix a potential NPE detected by sonarcloud:
https://sonarcloud.io/project/issues?id=vogellacompany_eclipse.platform.ui&open=AWjswuoYnCStnrhvQyge&resolved=false&types=BUG

Change-Id: Ibdb4bf2dee7b6b75897c18f8c516988e82347d2c
Signed-off-by: Justin Kuenzel <java@jukusoft.com>