Add note about predicate expressions

[sylveon]

Summary

I feel that quite a lot of uses of the throw; statement can be written in a more clean fashion by using a predicate expression (catch (...) when(condition)), so I've added a note in the try-catch documentation about it.

[BillWagner]

This is a great addition @sylveon We'd like to publicize the exception filter feature and encourage its use where it creates simpler code.

Over time, I want to update all the samples to show the preferred behavior.

I did have one change request. Can you just push that change to the same branch? Then, I'll

Thank you for contributing to docs. 🎆

[BillWagner]

Instead of "predicate expression", I'd prefer the term "exception filter".

[rpetrusha]

Some additional suggested changes, @sylveon:

• a often -->an often
• than the precedent example, --> as the previous example.
• the function --> The function
• null --> `null`

[sylveon]

I was following the name used a bit before in the same document.

Using catch arguments is one way to filter for the exceptions you
want to handle. You can also use a predicate expression that further
examines the exception to decide whether to handle it. If the
predicate expression returns false, then the search for a handler continues.

Should I change that too while I'm at it @BillWagner?

@rpetrusha will do.

[BillWagner]

thanks @sylveon Yes, let's change it in both locations

[sylveon]

Done and done.

[BillWagner]

Thanks for making this changes @sylveon

I'll now. You should see the changes on the live site in the next day or two.

Thanks again for contributing to docs! 🎆