NPE occurs when generating dot file of an NFA

[Mivik]

I chose exactly the lexer in examples/simple and appended "-dot" argument. Then the following NPE occurred:

../../bin/jflex -d out/genfiles -dot src/main/jflex/simple.flex
Reading "src/main/jflex/simple.flex"
Constructing NFA : 
Unexpected exception encountered. This indicates a bug in JFlex.
Please consider filing an issue at http://github.com/jflex-de/jflex/issues/new

java.lang.NullPointerException
	at jflex.core.NFA.dotFormat(NFA.java:502)
	at jflex.core.NFA.writeDot(NFA.java:478)
	at jflex.generator.LexGenerator.generate(LexGenerator.java:80)
	at jflex.Main.generate(Main.java:320)
	at jflex.Main.main(Main.java:336)

It seems that you didn't notice that the StateSet in table can be null while generating the graph.

[lsf37]

Thanks for the report. Yes, you're right, it can be null and will in fact often be null. At least it should be easy to fix.

[regisd]

This issue should be easy to fix, either with a null-check, or using Optional.