Symfony version(s) affected: all

Description
We're updating Symfony Demo to 4.2.x-dev to find deprecations and bugs. Sadly, lots of deprecation logs show information that is not useful.

For example in this one, the error message is very clear ... but I want to see more context info, such as the file where this happens, ideally the line too, etc.

However, if I click on "Show trace", the info is not useful:

If I click on "Show context", I get the same "not useful" info:

Am I doing something wrong ... or should we improve this? Thanks!