I activated some checkboxes in the game.project file. Then I deactivated them again (I didn’t do a revert to the file itself). So the settings were the same as before. Then I tried “Build HTML and Launch”. It did build, but the game didn’t run. The Console in the browser stated following:
When I looked in my changed files panel I notized that the game.project file was still listed there. So I did a diff:
After I reverted the game.project file, the game did run perfectly again in the web browser.
I hope this helps.