mruby should print error properly

tools/mruby/mruby.c

@@ -196,9 +196,12 @@ main(int argc, char **argv)
       v = mrb_load_file_cxt(mrb, args.rfp, c);
     }
     mrbc_context_free(mrb, c);
-    if (!mrb->exc && args.check_syntax) {
+    if (args.check_syntax) {
       printf("Syntax OK\n");
     }
+    else if (!mrb_undef_p(v) && mrb->exc) {
+      mrb_p(mrb, mrb_obj_value(mrb->exc));
+    }
   }
   cleanup(mrb, &args);