Fix error message

src/Parser.php

@@ -181,7 +181,7 @@ class Parser
                     break;
 
                 default:
-                    throw new SyntaxError('Lexer or parser ended up in unsupported state.', $this->getCurrentToken()->getLine(), $this->stream->getSourceContext());
+                    throw new SyntaxError('The lexer or the parser ended up in an unsupported state.', $this->getCurrentToken()->getLine(), $this->stream->getSourceContext());
             }
         }