You must configure the selected text editor.

Problem/Motivation

Can't set a text editor on any text format after enabling Markdown module.

Steps to Reproduce

1. On a new install
2. Create a new text format "Simple HTML"
3. Limit the HTML
4. Set the Editor to CK Editor
5. Save = Success

1. Enable Markdown Module
2. Create a new text format "Test HTML
3. Limit the HTML
4. Set the Editor to CK Editor
5. Save = You must configure the selected text editor.