The error page should include the:

• entity ID
• entity label in the language if it exists

TBA by @Samantha_Alipio_WMDE decision about how the page should look & text

In T254888#6210624, @Addshore wrote:

The right place to catch the exception in this case might be in FullEntityParserOutputGenerator::getParserOutput (the exception will likely be the one from T255008)
Again catching the ApiRequestExecutionException from the fed props API client
Adding code such as:

		throw new ErrorPageError( 'some Title', 'foo' );

Correctly shows an error page rather than the evil exception.

We would be able to get the label and ID for including using something like:

		if( $entity instanceof FingerprintProvider ) {
			$labelForErrorMessage = $entity->getFingerprint()->getLabel( $this->languageCode );
		}

Simple using an ErrorPageError doesn't appear to make the page follow the standard MediaWiki error page style, and perhaps either:

• We need to look at some other error pages such as MWException and other things that extend ErrorPageError and see where the style comes from and match that
• Have another style/look designed by UX or product.

We decided to do this all as 1 task