Preload Hero images doesn't work after \ServerSideRendering

[06romix]

If used default sequence of transformers ServerSideRendering would move media attributes to custom CSS before Optimizer preload hero images.

Media attribute is removed in Transformer\ServerSideRendering::adaptBlockingAttributes()
And here we have check Transformer\PreloadHeroImage::generatePreload()

Should transformers have a different sequence?

[westonruter]

It seems you're right. The PreloadHeroImage transformer is coming after ServerSideRendering:

amp-toolbox-php/src/Optimizer/Configuration.php

Lines 45 to 55 in 6eee28f

	const DEFAULT_TRANSFORMERS = [
	AmpBoilerplate::class,
	ServerSideRendering::class,
	AmpRuntimeCss::class,
	AmpBoilerplateErrorHandler::class,
	TransformedIdentifier::class,
	PreloadHeroImage::class,
	RewriteAmpUrls::class,
	ReorderHead::class,
	OptimizeAmpBind::class,
	];

[schlessera]

Yes, indeed, we need to move PreloadHeroImage before ServerSideRendering.

I'm wondering if we also should have a lightweight mechanism to check ordering and throw warnings if inter-dependencies are not met, as people can freely re-arrange the transformers...

[06romix]

I've created request #209 for a fast fix and going to make order checking.

[schlessera]

First issue fixed via #209 and second issue superseded by #219.