There is a weird JS error, often followed by a Construct 2 error message when the preview browser cannot update an active preview in time. This can be forced by doing the steps below.
- Open any project in Construct 2 r269 (might also work for previous versions)
- Spam-click the "run layout" button
- Notice a JS error message* in the preview window
- Notice error message** inside Construct 2
Tested and could reproduce using Construct 2 r269 on Windows 7.