protected function is_valid_type( Icon_Picker_Type $type ) {
		foreach ( array( 'id', 'controller' ) as $var ) {
			$value = $type->$var;

			if ( empty( $value ) ) {
				trigger_error( esc_html( sprintf( 'Icon Picker: "%s" cannot be empty.', $var ) ) );
				return false;
			}
		}

		if ( isset( $this->types[ $type->id ] ) ) {
			trigger_error( esc_html( sprintf( 'Icon Picker: Icon type %s is already registered. Please use a different ID.', $type->id ) ) );
			return false;
		}

		return true;
	}