NullPointerException in LexerATNSimulator.execDFA

[JFinis]

I receive the following null pointer exception

line 1:1 token recognition error at: ' '
Exception in thread "main" java.lang.NullPointerException
    at org.antlr.v4.runtime.atn.LexerATNSimulator.execDFA(LexerATNSimulator.java:244)
    at org.antlr.v4.runtime.atn.LexerATNSimulator.match(LexerATNSimulator.java:155)
    at org.antlr.v4.runtime.Lexer.nextToken(Lexer.java:146)
    at org.antlr.v4.runtime.BufferedTokenStream.fetch(BufferedTokenStream.java:133)
    at org.antlr.v4.runtime.BufferedTokenStream.sync(BufferedTokenStream.java:127)
    at org.antlr.v4.runtime.CommonTokenStream.consume(CommonTokenStream.java:69)
    at org.antlr.v4.runtime.Parser.consume(Parser.java:351)
    at org.antlr.v4.runtime.Parser.match(Parser.java:135)
    at test.ANTLRv4Parser.ruler(ANTLRv4Parser.java:76)
    at Test.main(Test.java:19)

This is the used grammar (the one of issue #45)

    grammar ANTLRv4;

    ruler returns [String r]
      :  t=ID  ':' alts+=expr ('|' alts+= expr)* ';'
          {  $r = "x"; }
       ;

    strongExpr returns [String r]
      : ID                      { $r = "x"; }
      | '(' ep=parenExpr ')'            { $r = "x"; }
      | e1=strongExpr '?'             { $r = "x"; }
      ;  

    expr returns [String r]
      : e=strongExpr (e2=expr)? { $r = "x"; }
      | e1=expr '->' ID {$r = "x"; }
      ;

    parenExpr returns [String r]
      : e1=expr '|' e2=parenExpr { $r = "x"; }
      | expr              {$r = $expr.r; }
      ;

    ID  :   ('A'..'Z'|'a'..'z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*
        ;    

And here is a test input (similiar to the one of issue #45, only with spaces in between):

x : x ;

Code for parser execution:

    ANTLRv4Lexer lex = new ANTLRv4Lexer(new ANTLRInputStream(new FileInputStream(new File("test.input"))));
    CommonTokenStream tokens = new CommonTokenStream(lex);

    new ANTLRv4Parser(tokens).ruler();