handle case where the given language is unknown - refs #15794
handle case where the given language is unknown - refs #15794

bluelml/core,pmattern/server,nextcloud/server,pmattern/server,endsguy/server,jbicha/server,lrytz/core,sharidas/core,lrytz/core,endsguy/server,owncloud/core,pixelipo/server,bluelml/core,pollopolea/core,cernbox/core,endsguy/server,whitekiba/server,endsguy/server,whitekiba/server,cernbox/core,whitekiba/server,endsguy/server,owncloud/core,nextcloud/server,bluelml/core,owncloud/core,pmattern/server,lrytz/core,sharidas/core,sharidas/core,xx621998xx/server,pixelipo/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,IljaN/core,bluelml/core,whitekiba/server,IljaN/core,xx621998xx/server,sharidas/core,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,owncloud/core,owncloud/core,pollopolea/core,xx621998xx/server,IljaN/core,pollopolea/core,pixelipo/server,xx621998xx/server,cernbox/core,phil-davis/core,pixelipo/server,Ardinis/server,cernbox/core,IljaN/core,Ardinis/server,jbicha/server,sharidas/core,jbicha/server,Ardinis/server,bluelml/core,nextcloud/server,michaelletzgus/nextcloud-server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,pmattern/server,pixelipo/server,IljaN/core,jbicha/server,Ardinis/server,michaelletzgus/nextcloud-server,cernbox/core,xx621998xx/server,pmattern/server,whitekiba/server,pollopolea/core,pollopolea/core,lrytz/core,Ardinis/server,jbicha/server,lrytz/core