Compilation should fail even though ANTLR forgives a syntax error

It is possible to write a program which has syntax errors, which ANTLR still successfully compiles. This could a missing ";" in the world declaration. It's cool that ANTLR can do that, but *if* there is a syntax error, the cellmata compiler should terminate at some point.

Start by reproducing the missing semicolon in the world declaration and trace how ANTLR reports or recovers from the syntax error during compilation. Done means the cellmata compiler terminates when a syntax error is present instead of successfully compiling the program.

Written by the indexing model from the issue text.