mod_workshop: Error writing to database when adding example submission

The Error writing to database is displayed when adding an example submission for the mod_workshop activity.

1. Create a course.
2. Turn editing on.
3. Add a Workshop activity.
   • name: Workshop activity
   • description: Testing
   • Submission settings: Instructions for submission: Submit testing....
   • Submission settings: Submission type: (only) File attachment
   • Example submissions: Use examples: ticked/enable.
4. Save the Workshop settings and view the activity.
5. Click the "Setup phase" / Edit assessment form" link.
   • Aspect 1: Description: Test123.
6. Click "Save and preview".
7. For Aspect 1: Test 123
   • Grade for Aspect 1: 10 / 10
   • Comment for Aspect 1: Testing comments.
8. Click "Back to editing form".
9. Click "Save and close".
10. Visit back the Workshop activity and ensure that the Setup phase has green tick for the following:

• Set the workshop description
• Provide instructions for submission
• Edit assessment form

1. Click the "Add example submission" button to add a submission.
   • Title: s1.
   • Attachment: upload any file
2. Click "Save changes".

Result:
Error message displayed is displayed. Please refer to the attachments.

This happens because there is no content_editor when "online text" is not enabled/allowed as a submission type.