Encountered two children with the same key, `undefined-undefined`.

[wilddog93]

hi guys, I found this issue when it was installed in next js,

next-dev.js?3515:32 Warning: Encountered two children with the same key, undefined-undefined. Keys should be unique so that components maintain their identity across updates. Non-unique keys may cause children to be duplicated and/or omitted — the behavior is unsupported and could change in a future version.

cause it cannot filter any values,

[amcdnl]

Can you share a demo link ( codesandbox or something )?