Fix database error when profile fields are missing

qa-include/plugins/qa-filter-basic.php

@@ -104,7 +104,9 @@ class qa_filter_basic
 
 	public function filter_profile(&$profile, &$errors, $user, $oldprofile)
 	{
-		foreach ($profile as $field => $value) {
+		foreach (array_keys($profile) as $field) {
+			// ensure fields are not NULL
+			$profile[$field] = (string) $profile[$field];
 			$this->validate_field_length($errors, $profile, $field, 0, QA_DB_MAX_CONTENT_LENGTH);
 		}
 	}