stop program when there are errors in parser

src/main/java/de/maishai/Compiler.java

@@ -45,6 +45,9 @@ public class Compiler {
         for (String error : errorListener.getErrors()) {
             LOGGER.severe(error);
         }
+        if (!errorListener.getErrors().isEmpty()) {
+            throw new RuntimeException("Errors during parsing");
+        }
         return new Program(classes);
     }