Fail Less Hard

I just encountered https://www.drupal.org/project/minifyhtml/issues/3041125

The module failed in a way that rendered the page mostly white and unusable. Since we know that if "%MINIFYHTML_" is left on the page after minifyhtml finishes, the minification failed, I think the module can fail and let a user still use the page.

I've provided a patch that checks if "%MINIFYHTML_" is still in the code, and if it is, resets the page to the original un-minified code. Then it sets a watchdog warning so admins will know the page isn't minified.

The patch could be better if we added an admin interface to control if the module fails hard or soft. With the setting disabled you can trace how the page failed a little easier. While it is enabled regular users encounter a working page and face no interruption of service.