discourse/discourse · error · Error

blockCondition: "validate" must be a function, got ${typeof

Error message

blockCondition: "validate" must be a function, got ${typeof validateFn}.

What it means

Error "blockCondition: "validate" must be a function, got ${typeof validateFn}." thrown in discourse/discourse.

Source

Thrown at frontend/discourse/app/blocks/conditions/decorator.ts:208

      `blockCondition: unknown config key(s): ${suggestions}. ` +
        `Valid keys are: ${VALID_CONFIG_KEYS.join(", ")}.`
    );
  }

  // Validate args schema at decoration time (catches schema definition errors)
  if (argsSchema && typeof argsSchema === "object") {
    validateConditionArgsSchema(argsSchema, type);
  }

  // Validate constraints schema at decoration time
  if (constraints) {
    // Constraints reference args schema - validate they're compatible
    validateConstraintsSchema(constraints, argsSchema, `Condition "${type}"`);
  }

  // Validate that validate is a function if provided
  if (validateFn !== undefined && typeof validateFn !== "function") {
    throw new Error(
      `blockCondition: "validate" must be a function, got ${typeof validateFn}.`
    );
  }

  // Freeze schema and compute derived validArgKeys
  const frozenSchema: Readonly<Record<string, ArgSchema>> = Object.freeze({
    ...argsSchema,
  });
  const frozenConstraints: Readonly<BlockConstraints> | undefined = constraints
    ? Object.freeze({ ...constraints })
    : undefined;
  const argKeys: readonly string[] = Object.freeze(Object.keys(argsSchema));
  const allKeys: readonly string[] =
    sourceType !== "none" ? Object.freeze([...argKeys, "source"]) : argKeys;

  return (TargetClass) => {
    // Validate that the class extends BlockCondition
    if (!(TargetClass.prototype instanceof BlockCondition)) {

View on GitHub (pinned to 1b2d7253e8)

When it happens

Trigger: Thrown at frontend/discourse/app/blocks/conditions/decorator.ts:208 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of discourse/discourse@1b2d7253e8 (2026-08-26). Data as JSON: /api/errors/619752d12bf344e5. Report an issue: GitHub.