[ErrorHandler] Prevent conflicts with WebProfilerBundle’s JavaScript

[MatTheCat]

Q	A
Branch?	5.4
Bug fix?	yes
New feature?	no
Deprecations?	no
Tickets	Fix #50108
License	MIT
Doc PR	N/A

ErrorHandler’s exception.js and WebProfilerBundle’s base_js.html.twig both expose a global Sfjs variable, which create conflicts (see linked issue e.g.).

As the exception page

• does not make use of Sfjs
• is not extensible

I updated exception.js to not create any global scope variable. I also removed DOMContentLoaded listeners as the script is run inline at the end of the document.

This PR stems from #48037.
Hiding whitespaces will produce a much more readable diff.

[yceruto]

LGMT, thanks!

[fabpot]

Thank you @MatTheCat.