Asset reference mappers are hiding bugs

[e1himself]

This is the same problem as #44 but on Asset resolution.

This catch-all exception inside asset reference nodes are hiding any error occurring during the link resolution. That includes:

• AssetHyperlink
• EmbeddedAssetBlock
• EmbeddedAssetInline

The problem with this approach is that the external code doesn't know if there was an exception. It just gets an incomplete object with some assets not fetched. The problem gets worse when these incomplete objects get cached (in contentful SDK or on CDN). While if there was an error thrown, the asset could be refetched on next request.

An example of code that causes this problem:

try {
    /** @var AssetInterface $asset */
    $asset = $linkResolver->resolveLink(
        new Link($linkData['id'], $linkData['linkType'])
    );
} catch (\Throwable $exception) {
    throw new MapperException($data);
}