Error Class 'ModernTimeline\ResultFacade\ResultFormatRegistry' not found

[Hua0Zi]

• MW version: 1.35.4
• PHP version: 7.4.9
• DB (MySQL etc.): 8.0.21
• SMW version:3.2.3
  -Modern Timeline version :1.2.1

Issue：

when I input "format=moderntimeline",then I will get the Error:

Here is the code:

If I delete the “format=moderntimeline” ，It will be ok：

Then I went to folder and open the file "mediawiki\extensions\ModernTimeline\src\ModernTimelinePrinte.php"，I could find the Class :

Here is the issue I met.Could you please give me a hand?

[Hua0Zi]

Please~