internal error: ArrayIndexOutOfBoundsException with imported Lexers

[166MMX]

Getting this ArrayIndexOutOfBoundsException while trying to generate a Parser and it's Lexers

The tool seems to have issues with the HT fragment inside the WS fragment of the ZConfHelpLexer.g grammar

8:57:35 PM: Executing external task 'generateGrammarSource'...
error(10):  internal error: jconfig/src/main/antlr3/com/initvoid/jconfig/zconf/ZConfParser.g : java.lang.ArrayIndexOutOfBoundsException: 2
org.antlr.tool.Rule.trackRuleReferenceInAlt(Rule.java:294)
org.antlr.tool.Grammar.altReferencesRule(Grammar.java:2011)
org.antlr.grammar.v3.DefineGrammarItemsWalker.atom(DefineGrammarItemsWalker.java:3197)
org.antlr.grammar.v3.DefineGrammarItemsWalker.element(DefineGrammarItemsWalker.java:2089)
org.antlr.grammar.v3.DefineGrammarItemsWalker.alternative(DefineGrammarItemsWalker.java:1738)
org.antlr.grammar.v3.DefineGrammarItemsWalker.block(DefineGrammarItemsWalker.java:1639)
org.antlr.grammar.v3.DefineGrammarItemsWalker.rule(DefineGrammarItemsWalker.java:1254)
org.antlr.grammar.v3.DefineGrammarItemsWalker.rules(DefineGrammarItemsWalker.java:981)
org.antlr.grammar.v3.DefineGrammarItemsWalker.grammarSpec(DefineGrammarItemsWalker.java:572)
org.antlr.grammar.v3.DefineGrammarItemsWalker.grammar_(DefineGrammarItemsWalker.java:271)
org.antlr.tool.Grammar.defineGrammarSymbols(Grammar.java:791)
org.antlr.tool.CompositeGrammar.defineGrammarSymbols(CompositeGrammar.java:379)
org.antlr.Tool.process(Tool.java:484)
org.antlr.Tool.main(Tool.java:98)
:generateGrammarSource FAILED

cmd args

-o jconfig/build/generated-src/main/java
jconfig/src/main/antlr3/com/initvoid/jconfig/zconf/ZConf.g
jconfig/src/main/antlr3/com/initvoid/jconfig/zconf/ZConfHelpLexer.g
jconfig/src/main/antlr3/com/initvoid/jconfig/zconf/ZConfMainLexer.g

'org.antlr:antlr:3.5.2'

$ java -version
java version "1.8.0_11"
Java(TM) SE Runtime Environment (build 1.8.0_11-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.11-b03, mixed mode)

Grammar files: https://gist.github.com/166MMX/3c51992164f001db652a