Method assertWritableKey

src/metaController.ts:667–671

* Throw if `key` is a reserved object-machinery name that can never be written * as a frontmatter property (see isReservedFrontmatterKey). Centralizes * the refusal so every dynamic `frontmatter[key] = value` sink in the controller * - `addYamlProp`, `updatePropertyInFile`, `u

(key: string)

     * the change (or polluting the prototype) while reporting success.
     */
    private assertWritableKey(key: string): void {
        if (isReservedFrontmatterKey(key)) {
            throw new Error(`"${key}" is a reserved property name and cannot be written to frontmatter.`);
        }
    }

    private async updateMultipleInFile(properties: Property[], file: TFile): Promise<void> {
        // Refuse a batch with ANY reserved YAML key BEFORE the write starts. This