Hi,
this is my first issue, so I hope I did everything right. We have been using version 7.21.0.Final of Drools for the last few months. A few weeks ago we switched to the latest version and could not import a few of our decision models (.dmn) anymore. According to our own research the bug seems to be present since 7.22.0.t042 and is still present in the latest snapshot.

This is the relevant logging output: https://gist.github.com/oas/ec0f70585411d8c3f0266b7d2fd02ebc

I tried to narrow down the exception and it seems to be in the method checkVariableName of org.kie.dmn.feel.parser.feel11.FEELParser. errorChecker.hasErrors() is false, but it is not catched by the if statement in line 111. Because of this, errorChecker.getErrors() returns null instead of a List<FEELEvent>.

The method checkVariableName in org.kie.dmn.core.compiler.DMNCompilerHelper, assumes that a list will be returned and calls isEmpty(). This throws the NullPointerException.