ACL\Login fix for UNIT DEFAULT return

It has to be int or null but because the SQL result is undefined (string)
it needs to be converted on return if it is a numeric value, else
null will be returned (it is the edit access id PK so it has to be
numeric)

www/lib/CoreLibs/ACL/Login.php

@@ -1058,9 +1058,9 @@ class Login
 					];
 					// set the default unit
 					if ($res['edit_default']) {
-						$_SESSION['UNIT_DEFAULT'] = $res['edit_access_id'];
+						$_SESSION['UNIT_DEFAULT'] = (int)$res['edit_access_id'];
 					}
-					$_SESSION['UNIT_UID'][$res['uid']] = $res['edit_access_id'];
+					$_SESSION['UNIT_UID'][$res['uid']] = (int)$res['edit_access_id'];
 					// sub arrays for simple access
 					array_push($eauid, $res['edit_access_id']);
 					$unit_acl[$res['edit_access_id']] = $res['level'];
@@ -2345,7 +2345,10 @@ HTML;
 			is_array($_SESSION['UNIT']) &&
 			!array_key_exists($edit_access_id, $_SESSION['UNIT'])
 		) {
-			return $_SESSION['UNIT_DEFAULT'] ?? null;
+			$edit_access_id = null;
+			if (is_numeric($_SESSION['UNIT_DEFAULT'])) {
+				$edit_access_id = (int)$_SESSION['UNIT_DEFAULT'];
+			}
 		}
 		return $edit_access_id;
 	}