Update watch observer value type to use DeepPartialSkipArrayKey

[LiamMartens]

I believe this is more accurate since undefined items in arrays should not be valid, please correct me if this is not correct

[codesandbox[bot]]

Review or Edit in CodeSandbox

Open the branch in Web Editor • VS Code • Insiders
Open Preview

[stale[bot]]

Thank you for your contributions! This Pull Request has been automatically marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. Best, RHF Team ❤️

[LiamMartens]

@bluebill1049 in case you're able to have a quick look for input :smile:

[bluebill1049]

hi @LiamMartens could you share an actual use case?

[beck-peterson]

I'm currently running into this issue. I can resolve it by casting the watched callback argument to a DeepPartialSkipArrayKey variant, but it would be nice to not have to.