DivisionByZeroError on AspectSwitcherImageEffect

Patch from MR. If either width or height is not a positive number do not return a style name.

https://git.drupalcode.org/project/image_effects/-/merge_requests/32/dif...

Thanks.

1) instead of returning in getChildImageStyleToExecute, I'd rather avoid to call it in applyEffect and transformDimensions when the image is invalid.
2) an automated test would help prevent regressions.

There is a duplicated issue #3136292: Division by zero in AspectSwitcherImageEffect → which patch caused us

Error: Xdebug has detected a possible infinite loop, and aborted your script with a stack depth of '256' frames in is_int() (line 331 of core/lib/Drupal/Component/Utility/NestedArray.php).

This patch is fine though (and seems an easier approach) than the attached duplicated issue.