Prevent Breadcrumbs on 404 pages

[ouun]

This fixes the PHP error Undefined array key 404. Thought about adding a specific key for that case, but as the content is not found it is obsolete IMO.

[Log1x]

crumb/src/Crumb.php

Lines 163 to 167 in 6abbf11

	if (is_404()) {
	return $this->add(
	$this->config['404']
	);
	}

exists but it needs renamed. See #7