Svelte 5 @next.148 broke Layercake

[vipero07]

Describe the bug

After upgrading from 5.0.0-next.147 to 5.0.0-next.148 I get the following error in browser when navigating away from a sveltekit page that has a layercake component on it.

This issue persists in next.150 as well.

Reproduction

I am going to see if I can fully reproduce this outside of my project (its unfortunately rather large and complex so this may take some time) but the minimum dependencies are the following.

  "dependencies": {
    "@sveltejs/kit": "2.5.10",
    "@sveltejs/vite-plugin-svelte": "3.1.1",
    "layercake": "8.3.0",
    "svelte": "5.0.0-next.148",
    "vite": "5.2.12"
  },

Then you just have two page routes, one with a layercake component, navigate to it, and away from it.

https://replit.com/@yodaissmart/Svelte-500next148-error?v=1
Click the chart link in the nav bar, then click home.

Logs

TypeError: Cannot read properties of undefined (reading 'delete')
    at chunk-W4736B2D.js?v=5c3605ec:2198:18
    at execute_effect_teardown (chunk-HMLMMEOZ.js?v=5c3605ec:2028:16)
    at destroy_effect (chunk-HMLMMEOZ.js?v=5c3605ec:2048:3)
    at destroy_effect_children (chunk-HMLMMEOZ.js?v=5c3605ec:1274:5)
    at destroy_effect (chunk-HMLMMEOZ.js?v=5c3605ec:2040:3)
    at destroy_effect_children (chunk-HMLMMEOZ.js?v=5c3605ec:1274:5)
    at destroy_effect (chunk-HMLMMEOZ.js?v=5c3605ec:2040:3)
    at destroy_effect_children (chunk-HMLMMEOZ.js?v=5c3605ec:1274:5)
    at destroy_effect (chunk-HMLMMEOZ.js?v=5c3605ec:2040:3)
    at destroy_effect_children (chunk-HMLMMEOZ.js?v=5c3605ec:1274:5)

The specific location of that error is the line listeners2.delete(listener); in the following chunk.

// node_modules/svelte/src/internal/client/dom/elements/bindings/size.js
var _listeners, _observer, _options, _getObserver, getObserver_fn;
var _ResizeObserverSingleton = class _ResizeObserverSingleton {
  /** @param {ResizeObserverOptions} options */
  constructor(options) {
    __privateAdd(this, _getObserver);
    /** */
    __privateAdd(this, _listeners, /* @__PURE__ */ new WeakMap());
    /** @type {ResizeObserver | undefined} */
    __privateAdd(this, _observer, void 0);
    /** @type {ResizeObserverOptions} */
    __privateAdd(this, _options, void 0);
    __privateSet(this, _options, options);
  }
  /**
   * @param {Element} element
   * @param {(entry: ResizeObserverEntry) => any} listener
   */
  observe(element2, listener) {
    var listeners = __privateGet(this, _listeners).get(element2) || /* @__PURE__ */ new Set();
    listeners.add(listener);
    __privateGet(this, _listeners).set(element2, listeners);
    __privateMethod(this, _getObserver, getObserver_fn).call(this).observe(element2, __privateGet(this, _options));
    return () => {
      var listeners2 = __privateGet(this, _listeners).get(element2);
      listeners2.delete(listener);
      if (listeners2.size === 0) {
        __privateGet(this, _listeners).delete(element2);
        __privateGet(this, _observer).unobserve(element2);
      }
    };
  }
};

System Info

System:
    OS: macOS 14.4.1
    CPU: (12) arm64 Apple M2 Max
    Memory: 875.78 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.13.1 - /private/var/folders/14/ghm2196s181_vf_0g1425s7m0000gn/T/xfs-ca02c7c1/node
    Yarn: 4.1.1 - /private/var/folders/14/ghm2196s181_vf_0g1425s7m0000gn/T/xfs-ca02c7c1/yarn
    npm: 10.5.2 - ~/.volta/tools/image/node/20.13.1/bin/npm
  Browsers:
    Brave Browser: 121.1.62.156
    Safari: 17.4.1
  npmPackages:
    svelte: 5.0.0-next.148 => 5.0.0-next.148

Severity

blocking an upgrade

[vipero07]

A simple solution is to just ensure listeners2 is not undefined before calling delete on it. Though this may result in a memory leak, I'm not familiar enough with the underlying code.

[vipero07]

Here is a repl https://replit.com/@yodaissmart/Svelte-500next148-error?v=1
Click the chart link in the nav bar, then click home.

[asadbek2304]

Any updates on this?