exit non zero on error

build.zig

@@ -621,7 +621,7 @@ const ZiglingStep = struct {
 
             print("\n{s}Edit exercises/{s} and run this again.{s}", .{ red_text, self.exercise.main_file, reset_text });
             print("\n{s}To continue from this zigling, use this command:{s}\n    {s}zig build {s}{s}\n", .{ red_text, reset_text, bold_text, self.exercise.key(), reset_text });
-            std.os.exit(0);
+            std.os.exit(1);
         };
     }