The following query asks for distance from the page Huay Xai
https://en.wikivoyage.org/w/api.php?action=query&format=json&formatversion=2&codistancefrompage=Huay%20Xai&redirects=&prop=coordinates%7Cpageimages%7Cpageterms&titles=Chiang%20Khong%7CLuang%20Prabang%7CLuang%20Namtha%7CLuang%20Namtha%7CJinghong%7CMuang%20Xay%7CLuang%20Prabang%7CVientiane&pilimit=50&pithumbsize=120&colimit=max&wbptterms=description
... but since Huay Xai has no coordinates
I get the following response:
{"servedby":"mw1099","error":{"code":"co_no-coordinates","info":"Page ``Huay Xai'' has no primary coordinates","docref":"See https://en.wikivoyage.org/w/api.php for API usage"}}
(e.g. no page images and no coordinates... nothing)
Expected: This should throw a warning and simply omit the field coordinates.dist. Otherwise I have to query Huay Xai beforehand to see if it has coordinates.