Setting className on SwiperSlide triggers runtime error with React 18 in strict mode

[raphaelsaunier]

Check that this is really a bug

• I confirm

Reproduction link

https://codesandbox.io/s/practical-ganguly-w39dul?file=/pages/index.tsx

Bug description

Duplicate of #5613 and possibly related to #5398

Expected Behavior

I should be able to set a className on <SwiperSlide> components.

Actual Behavior

Setting a className triggers the following error, initially reported in #5613:

• Chrome: TypeError: Cannot read properties of undefined (reading 'slideClass')
• Safari: TypeError: undefined is not an object (evaluating 'swiper.params.slideClass')
• Firefox: TypeError: can't access property "slideClass", swiper.params is undefined

Swiper version

8.1.3

Platform/Target and Browser Versions

All browsers are affected

Validations

• Follow our Code of Conduct
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.
• Make sure this is a Swiper issue and not a framework-specific issue

Would you like to open a PR for this bug?

• I'm willing to open a PR