Fix SQL query for MSC labels lookup

[eloiferrer]

Describe the bug If a publication Item has a wrong MSC code (for instance, an inexistant code, coming from a typo in zbmath) the SQL query to retrieve MSC labels in the Publication profile page fails completely for all codes.

Example: https://portal.mardi4nfdi.de/wiki/Publication:4713262

Expected behavior The MSC labels corresponding to the remaining correct MSC codes should be displayed.

Additional context Documentation on the function from the ExternalData documentation to run the SQL query: https://www.mediawiki.org/wiki/Extension:External_Data/Databases

Checklist for this issue: (Some checks for making sure this issue is completely formulated)

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[eloiferrer]

Solved, see: https://portal.mardi4nfdi.de/w/index.php?title=Module%3APublicationMSCList&diff=34313209&oldid=34076066

MSC codes that do not return results from the SQL table (possibly because they are wrong) are ignored in the rendering of the publication template, which happens in the PublicationMSCList.