Shell 3.26 / GJS Strict Mode settings

[Jason DeRose <list derose io>]

Can someone give me more information on the changes in 3.26 that have
lead to the increased number of warnings in GJS?

For example, equality comparison to an undefined variable now logs a
warning. But, not all uses of an undefined variable throw a warning, and
I would expect to see an error if the engine was running purely in
strict mode.

So basically I'm just curious as to what specifically has changed so I
can ensure my code is compliant with the engine's expectations?

Thanks!
- Jason