src/vs/base/common/codicons.ts/Registry/add
class Registry:	public add(icon: Codicon) {
		const existing = this._icons.get(icon.id);
		if (!existing) {
			this._icons.set(icon.id, icon);
			this._onDidRegister.fire(icon);
		} else if (icon.description) {
			existing.description = icon.description;
		} else {
			console.error(`Duplicate registration of codicon ${icon.id}`);
		}
	}