Steps to reproduce the issue

Publish a mod_tags_popular in frontend
Since the merge of 3.10-dev into 4.0 we have an error which breaks frontend display

Notice: Array to string conversion in .../modules/mod_tags_popular/src/Helper/TagsPopularHelper.php on line 100
Error: Unknown column 'Array' in 'where clause': Unknown column 'Array' in 'where clause'

Code merged was

-			->whereIn($db->quoteName('c.core_access'), $groups)
+			->where('(' . $db->quoteName('c.core_access') . ' IN (' . $groups . ') OR ' . $db->quoteName('c.core_access') . ' = 0)')

@wilsonge