Whether or not the spider gene is homozygous lethal, you would still get normals when breeding spider to spider(assuming neither is the legendary homozygous spider). Each parent has a 50/50 chance of passing the gene, so there is a chance they could both not pass the gene. Same goes for breeding pastel to pastel or lesser to lesser(insert any other codom here), you can produce normals with these pairings.

The only time you will not produce normals is if one parent is homozygous for a codom trait(ie super pastel or super lesser bel), or if both parents are homozygous recessives.