OrchardCMS/OrchardCore · error · TypeError

@@toPrimitive must return a primitive value.

Error message

@@toPrimitive must return a primitive value.

What it means

Internal helper in the bundled Font Awesome UMD bundle: _toPrimitive calls the value's Symbol.toPrimitive method and the result is an object instead of a primitive. This is a transpiled runtime invariant failure, not an Orchard Core error — it occurs only when consumer script passes exotic objects into Font Awesome APIs. Fix by updating the vendored fontawesome package or reporting upstream.

Solutions

1. Ensure Symbol.toPrimitive returns a primitive value
2. Audit and remove polyfills that override Symbol/Object prototype behavior
3. Regenerate or update the regular.js vendor bundle

Example fix

// before
key[Symbol.toPrimitive] = () => new Object();
// after
key[Symbol.toPrimitive] = (hint) => hint === 'string' ? 'key' : 1;

function safeKey(o) { if (typeof o?.[Symbol.toPrimitive] === 'function') { const r = o[Symbol.toPrimitive]('string'); if (typeof r === 'object') throw new TypeError('toPrimitive returned object'); return r; } return o; }

function hasPrimitiveToPrimitive(o) { const f = o?.[Symbol.toPrimitive]; return typeof f !== 'function' || ['string','number','symbol'].includes(typeof f.call(o, 'string')); }

try { loadRegularIcons(); } catch (e) { if (e instanceof TypeError && e.message.includes('toPrimitive')) console.error('Polyfill conflict detected'); }

When it happens

Trigger: A computed property / key conversion in regular.js hitting an object whose Symbol.toPrimitive(hint) returns {} or another non-primitive.

Common situations: Global polyfill conflicts; monkey-patching Object/Symbol prototypes on the page; corrupted or mismatched vendor bundles shipped together.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• @@toPrimitive must return a primitive value.
• @@toPrimitive must return a primitive value.
• Super expression must either be null or a function
• @@toPrimitive must return a primitive value.
• Invalid attempt to destructure non-iterable instance. In…

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/f952610d5ec81bfd. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore.Modules/OrchardCore.Resources/wwwroot/Vendor/fontawesome-free-6.7.2/js/regular.js:59

  }
  function _objectSpread2(e) {
    for (var r = 1; r < arguments.length; r++) {
      var t = null != arguments[r] ? arguments[r] : {};
      r % 2 ? ownKeys(Object(t), !0).forEach(function (r) {
        _defineProperty(e, r, t[r]);
      }) : Object.getOwnPropertyDescriptors ? Object.defineProperties(e, Object.getOwnPropertyDescriptors(t)) : ownKeys(Object(t)).forEach(function (r) {
        Object.defineProperty(e, r, Object.getOwnPropertyDescriptor(t, r));
      });
    }
    return e;
  }
  function _toPrimitive(t, r) {
    if ("object" != typeof t || !t) return t;
    var e = t[Symbol.toPrimitive];
    if (void 0 !== e) {
      var i = e.call(t, r || "default");
      if ("object" != typeof i) return i;
      throw new TypeError("@@toPrimitive must return a primitive value.");
    }
    return ("string" === r ? String : Number)(t);
  }
  function _toPropertyKey(t) {
    var i = _toPrimitive(t, "string");
    return "symbol" == typeof i ? i : i + "";
  }

  var S = {
      classic: {
        fa: "solid",
        fas: "solid",
        "fa-solid": "solid",
        far: "regular",
        "fa-regular": "regular",
        fal: "light",
        "fa-light": "light",
        fat: "thin",

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