Go to beta cswiki, select the link recommendation task for Emma Hewitt (or just click on https://cs.wikipedia.beta.wmflabs.org/wiki/Speci%C3%A1ln%C3%AD:Homepage/newcomertask/241?geclickid=5036q73hc4c8nk8jvji0vsegkierfgep&getasktype=link-recommendation ) and open the article for editing. VisualEditor will die halfway with this error message:
jQuery.Deferred exception: Cannot read property 'link_target' of undefined TypeError: Cannot read property 'link_target' of undefined at AddLinkDesktopArticleTarget.AddLinkArticleTarget.annotateSuggestions (<anonymous>:6:647) at AddLinkDesktopArticleTarget.AddLinkArticleTarget.beforeLoadSuccess (<anonymous>:3:218) at AddLinkDesktopArticleTarget.loadSuccess (<anonymous>:2:303) at fire (https://cs.wikipedia.beta.wmflabs.org/w/load.php?lang=en&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets&skin=vector&version=1vuvy:46:209) at fireWith (https://cs.wikipedia.beta.wmflabs.org/w/load.php?lang=en&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets&skin=vector&version=1vuvy:47:402) at mightThrow (https://cs.wikipedia.beta.wmflabs.org/w/load.php?lang=en&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets&skin=vector&version=1vuvy:49:751) at process (https://cs.wikipedia.beta.wmflabs.org/w/load.php?lang=en&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets&skin=vector&version=1vuvy:49:808) at https://cs.wikipedia.beta.wmflabs.org/w/load.php?lang=en&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets&skin=vector&version=1vuvy:50:37 at mightThrow (https://cs.wikipedia.beta.wmflabs.org/w/load.php?lang=en&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets&skin=vector&version=1vuvy:49:149) at process (https://cs.wikipedia.beta.wmflabs.org/w/load.php?lang=en&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets&skin=vector&version=1vuvy:49:808)
At a glance the DB record seems OK:
MariaDB [cswiki]> select * from growthexperiments_link_recommendations where gelr_page = 241 \G *************************** 1. row *************************** gelr_revision: 245 gelr_page: 241 gelr_data: {"links":[{"link_text":"Finsku","link_target":"Finsko","match_index":0,"wikitext_offset":1360,"score":0.567171037197113,"context_before":" m\u00edsto ve ","context_after":". Singl se","link_index":0},{"link_text":"Decade","link_target":"Decade","match_index":0,"wikitext_offset":3268,"score":0.6700974106788635,"context_before":"pres. Sun ","context_after":" feat. Emm","link_index":1},{"link_text":"Berlin","link_target":"Berl\u00edn","match_index":1,"wikitext_offset":3520,"score":0.8429474830627441,"context_before":"11 - Dash ","context_after":" feat. Emm","link_index":2},{"link_text":"Miss You","link_target":"Miss You","match_index":0,"wikitext_offset":3869,"score":0.9231995940208435,"context_before":" Hewitt - ","context_after":" Paradise\n","link_index":3}]} 1 row in set (0.00 sec)