Can't start Plugin with IntelliJ 2019.3-EAP

Hi there,

I received a feature request to add support for 2019.3 to my plugin, 

however I get the crash:

$./gradlew :runIde
> Task :generateParser FAILED
Exception in thread "main" java.lang.ExceptionInInitializerError
        at org.intellij.grammar.Main.main(Main.java:49)
Caused by: java.lang.RuntimeException: java.lang.NullPointerException
        at org.intellij.grammar.LightPsi.<clinit>(LightPsi.java:99)
        ... 1 more
Caused by: java.lang.NullPointerException
        at com.intellij.util.messages.MessageBusFactory.newMessageBus(MessageBusFactory.java:24)
        at org.intellij.grammar.LightPsi$Init.initAppAndProject(LightPsi.java:288)
        at org.intellij.grammar.LightPsi$MyParsing.<init>(LightPsi.java:196)
        at org.intellij.grammar.LightPsi.<clinit>(LightPsi.java:96)
        ... 1 more

FAILURE: Build failed with an exception.

I've tried updating gradle as well as the intellij and grammar kit plugins to the latest version and there is no change.

A PR of the changes I made (as well as plugin source code is available here):

https://github.com/SJrX/systemdUnitFilePlugin/pull/83/files