Source

File: wp-admin/includes/class-theme-installer-skin.php

public function hide_process_failed( $wp_error ) {
		if (
			'upload' === $this->type &&
			'' === $this->overwrite &&
			$wp_error->get_error_code() === 'folder_exists'
		) {
			return true;
		}

		return false;
	}