NPE in external tool configurations

[OverDrone]

Steps to reproduce:

1. Create gradle project (any type)
2. build it
3. select run as/gradle build
4. select run as/external tool configuration
5. left click on any item in tree on the left beside gradle build configurations. i.e. 'program', 'ant build', etc
6. Most irritating thing is that after that eclipse response to any action with exception, so you must kill process

If you somehow delete all gradle external tool configurations this bug is no more reproduced. You can navigate and left click on any item in the tree
log file https://gist.github.com/OverDrone/45abdec4daca2489cbe5