IguanaCLI RuntimeException: org.iguana.grammar.symbol.Nonterminal; incompatible types for field nodeType

[jip]

run from IntelliJ IDEA:

> /usr/lib64/jvm/java/bin/java -Dfile.encoding=UTF-8 -classpath "..." org.iguana.util.IguanaCLI -g target/classes/IggyGrammar -s A

Exception in thread "main" java.lang.RuntimeException: java.io.InvalidClassException: org.iguana.grammar.symbol.Nonterminal; incompatible types for field nodeType
	at org.iguana.grammar.Grammar.load(Grammar.java:349)
	at org.iguana.grammar.Grammar.load(Grammar.java:337)
	at org.iguana.grammar.Grammar.load(Grammar.java:332)
	at org.iguana.util.IguanaCLI.main(IguanaCLI.java:73)
Caused by: java.io.InvalidClassException: org.iguana.grammar.symbol.Nonterminal; incompatible types for field nodeType
	at java.io.ObjectStreamClass.matchFields(ObjectStreamClass.java:2299)
	at java.io.ObjectStreamClass.getReflector(ObjectStreamClass.java:2193)
	at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:669)
	at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1630)
	at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1781)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1353)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:373)
	at java.util.HashMap.readObject(HashMap.java:1402)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1058)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1909)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1808)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1353)
	at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2018)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1942)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1808)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1353)Disconnected from the target VM, address: '127.0.0.1:45890', transport: 'socket'

	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:373)
	at org.iguana.grammar.Grammar.load(Grammar.java:346)
	... 3 more

Process finished with exit code 1