urn crash in luaj

crash.log

~/src/urn $ make test LUA=luaj
luaj bin/urn.lua tests/compiler/codegen/precedence --run -o /tmp/tmp.9mEtsMxCet -fstrict-structs -- 
org.luaj.vm2.LuaError: bin/urn.lua:2034 vm error: java.lang.ArrayIndexOutOfBoundsException: -1
stack traceback:
	bin/urn.lua:2034: in function 'parseDocstring1'
	bin/urn.lua:10481: in function 'validate'
	bin/urn.lua:10501: in function 'run'
	bin/urn.lua:2858: in function 'runPass1'
	bin/urn.lua:10583: in function '?'
	bin/urn.lua:11332: in main chunk
	[Java]: in ?
	at org.luaj.vm2.LuaClosure.execute(Unknown Source)
	at org.luaj.vm2.LuaClosure.call(Unknown Source)
	at org.luaj.vm2.LuaClosure.execute(Unknown Source)
	at org.luaj.vm2.LuaClosure.onInvoke(Unknown Source)
	at org.luaj.vm2.LuaClosure.invoke(Unknown Source)
	at org.luaj.vm2.LuaClosure.execute(Unknown Source)
	at org.luaj.vm2.LuaClosure.onInvoke(Unknown Source)
	at org.luaj.vm2.LuaClosure.invoke(Unknown Source)
	at org.luaj.vm2.LuaClosure.execute(Unknown Source)
	at org.luaj.vm2.LuaClosure.onInvoke(Unknown Source)
	at org.luaj.vm2.LuaClosure.invoke(Unknown Source)
	at org.luaj.vm2.LuaClosure.execute(Unknown Source)
	at org.luaj.vm2.LuaClosure.onInvoke(Unknown Source)
	at org.luaj.vm2.TailcallVarargs.eval(Unknown Source)
	at org.luaj.vm2.TailcallVarargs.arg1(Unknown Source)
	at org.luaj.vm2.LuaClosure.call(Unknown Source)
	at org.luaj.vm2.LuaClosure.execute(Unknown Source)
	at org.luaj.vm2.LuaClosure.onInvoke(Unknown Source)
	at org.luaj.vm2.LuaClosure.invoke(Unknown Source)
	at lua.processScript(Unknown Source)
	at lua.main(Unknown Source)
Caused by: java.lang.ArrayIndexOutOfBoundsException: -1
	at org.luaj.vm2.lib.StringLib$MatchState.match_class(Unknown Source)
	at org.luaj.vm2.lib.StringLib$MatchState.matchbracketclass(Unknown Source)
	at org.luaj.vm2.lib.StringLib$MatchState.match(Unknown Source)
	at org.luaj.vm2.lib.StringLib$MatchState.start_capture(Unknown Source)
	at org.luaj.vm2.lib.StringLib$MatchState.match(Unknown Source)
	at org.luaj.vm2.lib.StringLib.str_find_aux(Unknown Source)
	at org.luaj.vm2.lib.StringLib$find.invoke(Unknown Source)
	... 21 more