ve.ce.MWTransclusionNode: Check for API errors

See ApiVisualEditor.php#parsefragment.

Error code is also incorrectly about Parsoid, method
parseWikitextFragment does a FauxRequest to MediaWiki. Fixed
error.info. Keeping the same error.code for now for consistency.

Bug: 52483
Change-Id: Ic473ae4a5c1e9706140f6ec4cc8157fadd02c318