So. Now we build our editor around a world object.

World was missing...

nbproject/project.properties

@@ -1,4 +1,4 @@
-#Sat, 01 Dec 2018 09:27:21 +0100
+#Wed, 05 Dec 2018 17:40:04 +0100
 annotation.processing.enabled=true
 annotation.processing.enabled.in.editor=false
 annotation.processing.processors.list=
@@ -100,7 +100,7 @@ manifest.custom.permissions=
 manifest.file=manifest.mf
 meta.inf.dir=${src.dir}/META-INF
 mkdist.disabled=false
-platform.active=JDK_1.11.0
+platform.active=default_platform
 project.license=bsd
 run.classpath=${javac.classpath}\:${build.classes.dir}
 # Space-separated list of JVM arguments used when running the project.