discourse/discourse · error · BlockError

${typeError.message}

Error message

${typeError.message}

What it means

Blocks schema validation: the argument's value was provided and its name is valid, but validateArgValue found a type/schema mismatch — the wrapped message is the underlying type error (wrong type, failed enum/pattern, or out-of-range value per the ArgSchema). The BlockError carries the sub-path from that validation.

Solutions

1. Read the inner message for the specific constraint, then coerce or change the value at the call site to the declared type.
2. If the declared type is wrong, update the ArgSchema in the @block decorator to match reality.
3. For enum/pattern constraints, use one of the declared values or fix the pattern.

When it happens

Trigger: Thrown at frontend/discourse/app/lib/blocks/-internals/validation/args.ts:1121 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/227fc649e9135eb2. Report an issue: GitHub.

Appendix: source

Thrown at frontend/discourse/app/lib/blocks/-internals/validation/args.ts:1121

      );
    }
  }

  for (const [argName, argDef] of Object.entries(schema)) {
    const value = providedArgs[argName];

    // 2. Check required args
    if (argDef.required && value === undefined) {
      throw new BlockError(`missing required ${pathPrefix}.${argName}.`, {
        path: `${pathPrefix}.${argName}`,
      });
    }

    // 3. Validate type if value is provided
    if (value !== undefined) {
      const typeError = validateArgValue(value, argDef, argName, options);
      if (typeError) {
        throw new BlockError(typeError.message, {
          path: `${pathPrefix}.${typeError.path}`,
        });
      }
    }
  }
}

View on GitHub (pinned to 1b2d7253e8)