clockworklabs/SpacetimeDB · error · TypeError

When providing a name, you must also provide the variants ob

Error message

When providing a name, you must also provide the variants object or array.

What it means

t.enum accepts either (variantsObj) for an anonymous sum or (name, variantsObj) for a named one. If the first argument is a string and the second is missing or falsy, there are no variants to build, so it throws TypeError - a name alone does not define a sum type.

Source

Thrown at crates/bindings-typescript/src/lib/type_builders.ts:3741

  /**
   * Creates a full sum type, where each case can have a payload.
   * Each value in the object must be a {@link TypeBuilder}.
   *
   * Example:
   * ```ts
   * t.enum("Result", { Ok: t.unit(), Err: t.string() });
   * ```
   */
  <Obj extends VariantsObj>(name: string, obj: Obj): SumBuilder<Obj>;
}

const enumImpl = ((nameOrObj: any, maybeObj?: any) => {
  let obj: any = nameOrObj;
  let name: string | undefined = undefined;

  if (typeof nameOrObj === 'string') {
    if (!maybeObj) {
      throw new TypeError(
        'When providing a name, you must also provide the variants object or array.'
      );
    }
    obj = maybeObj;
    name = nameOrObj;
  }

  // Simple sum (array form)
  if (Array.isArray(obj)) {
    const simpleVariantsObj: Record<string, UnitBuilder> = {};
    for (const variant of obj) {
      simpleVariantsObj[variant] = new UnitBuilder();
    }
    return new SimpleSumBuilderImpl(simpleVariantsObj, name);
  }

  // Regular sum (object form)
  return new SumBuilder(obj, name);

View on GitHub (pinned to 524b4487d9)

Solutions

Pass the variants: t.enum('Status', ['Active', 'Banned']) or t.enum('Status', { Active: t.unit(), Banned: t.string() })
Drop the name if anonymity is intended: t.enum({ ... }) or t.enum([...])

Example fix

// before
const status = t.enum('Status'); // -> TypeError

// after
const status = t.enum('Status', ['Active', 'Banned']);

Defensive patterns

Strategy: validation

Validate before calling

function enumArgsValid(nameOrObj: unknown, maybeObj: unknown): boolean {
  return typeof nameOrObj !== 'string' || Boolean(maybeObj);
}
// enumArgsValid(nameOrObj, maybeObj) before calling t.enum

Prevention

Always supply the variants object or array when naming an enum
Let the overload signatures guide you: name implies a second argument
Run schema construction in a startup smoke test so arity mistakes fail fast

When it happens

Trigger: t.enum('Status') - the name was given but the variants object or array was omitted.

Common situations: Partial refactors where the variants object is deleted or commented out; IDE autocomplete inserting only the first argument; merging schema code and losing the second argument.

Related errors

AI-assisted analysis of clockworklabs/SpacetimeDB@524b4487d9 (2026-08-16). Data as JSON: /api/errors/ed90ef8bb40929d8. Report an issue: GitHub.