CLI times out with an unhelpful error if --include element not found

[gpaciga]

When running axe-core/cli, if --include is set to a CSS selector that does not exist on the page, axe will hang until the timeout expires and then report a generic error, suggesting that an issue be filed here.

Expectation: The error message should say that no elements were found to scan

Actual: The user is directed here, suggesting they may have found a bug with axe-core or the CLI itself

Motivation: By being told what the error is, the user won't have to do extra debugging (as I did today for about half an hour before I realized my mistake!)

axe-core/cli version: 4.1.1

+ npx axe --no-color --chrome-options=no-sandbox,disable-gpu --include '#main' https://www.google.ca
Running axe-core 4.1.2 in chrome-headless

Testing https://www.google.ca ... please wait, this may take a minute.
 
An error occurred while testing this page.
Please report the problem to: https://github.com/dequelabs/axe-cli/issues/

Without --include '#main', the scan completes as expected. A similar scan on a page that does have an ID like those also works as expected:

npx axe --no-color --chrome-options=no-sandbox,disable-gpu --include '#page' https://dequeuniversity.com/

[padmavemulapati]

Validated with the latest @axe-core/cli(4.4.1-alpha.252 )
Seeing the valid error message when we try to add scope analysis on the test page and the selector not found within the page.

[Zidious]

Closing, no docs required.