fix: deinit on app error

turns a 7000 line stacktrace to only one, simple stacktrace.

src/app.zig

···
             .bg = null,
             .yellow = null,
         };
+        errdefer self.deinit();
 
         self.lua = try Lua.init(self.alloc);
         self.write_thread = try std.Thread.spawn(.{}, writeLoop, .{ self.alloc, &self.write_queue });