Wrap tsvector attributes with coalesce before join

Fixed a bug where joining multiple tsvector attributes results in NULL
because one of the columns contains NULL. The expected behaviour is to
ignore that column instead, which is achieved by setting it to an empty
string

packages/strapi-hook-bookshelf/lib/queries.js

@@ -546,8 +546,8 @@ const buildSearchQuery = (qb, model, params) => {
     case 'pg': {
       const searchQuery = searchText.map(attribute =>
         _.toLower(attribute) === attribute
-          ? `to_tsvector(${attribute})`
-          : `to_tsvector("${attribute}")`
+          ? `to_tsvector(coalesce(${attribute}, ''))`
+          : `to_tsvector(coalesce("${attribute}", ''))`
       );
 
       qb.orWhereRaw(`${searchQuery.join(' || ')} @@ plainto_tsquery(?)`, query);