Import pipeline is failing to load EaArX records because they fail in aip.classic.enforce_schema at L181

L181 is currently as follows: `r['arxivcategories'] = [i['#text'] if isinstance(i,dict) else i for i in eL(g('arxivcategories',{}).get('arxivcategory',[]))]`

If the dictionary key `'#text'` doesn't exist, this will throw an exception.

suggest changing it to `i.get('#text', None)`
