Neil Brown

See #11 -- global keyword followed by nothing causes an exception. This simple PR adds a test proving the issue, and then a fix which makes the test work. (I'm...

If you try to run on code like this: def func(): global Then TigerPython throws an exception like this: ``` java.lang.NullPointerException: Cannot invoke "tigerpython.parser.lexer.Token.pos()" because the return value of "tigerpython.parser.lexer.TokenBuffer.head()"...