Empty `directory_` index causes ES count query error

[derekenos]

When the directory_ index is empty, allIndices will be an empty array, which sets the count query terms index_ aggregation size to 0 which ES does not like.

Relevant code

const countQuery = {
     size: 0,
     query: searchQuery.query,
     aggs: {
       collection: {
         terms: {
           field: "_index",
           size: allIndices.length
         }
       }
     }
   }

JS Errors

Search error: [1:185] [terms] failed to parse field [size]
Uncaught (in promise) TypeError: countResponse is null