Custom EventWrapper with DnD extension not rendering correctly

[palagonKevo]

Check that this is really a bug

• I confirm

Reproduction link

https://codesandbox.io/p/sandbox/4rsg7w

Bug description

Custom EventWrapper with DnD add-on is bugged, it's not rendering correctly. Whenever you add a custom component in the components prop, it crashes and doesn't render the component at all.

Expected Behavior

Seems to be an issue while executing mergeComponents function, which is taking keys as undefined and the forEach function is stating that can't use forEach for undefined. In previous versions, this was working as expected.

Actual Behavior

The whole component is crashing

react-big-calendar version

^1.17.1

React version

^19.0.0

Platform/Target and Browser Versions

Any

Validations

• 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 react-big-calendar issue and not an implementation issue

Would you like to open a PR for this bug?

• I'm willing to open a PR

[7assenTlili]

@palagonKevo it looks like a compatibility issue with React 19. I downgraded React to 18 in your codesandbox example and it worked fine.

[palagonKevo]

Ok. I found a way to avoid using the eventWrapper in my use case, and I'll use that until this is fixed. At least is working somehow, but it would be great to know a way to solve this, I want to use the latest version to get the latest features.