[Lens] Fix wrong error detection on transition to Top values operation

[dej611]

Summary

Fixes #101758

The getErrorMessages method in the Top Values operation was returning an empty array in case of no errors rather than undefined, breaking the logic on the dimension editor detection for transition errors.
The regression was introduced within this release, so no need to report it externally.

This PR sets the correct result when the error array is empty.

Checklist

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[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[flash1293]

Tested and this works fine, but I don't find the place in the code where it was causing issues before. Could you explain what's going on?

[dej611]

getErrorMessage: (layer, columnId, indexPattern) =>
    [
      ...(getInvalidFieldMessage(
        layer.columns[columnId] as FieldBasedIndexPatternColumn,
        indexPattern
      ) || []),
      getDisallowedTermsMessage(layer, columnId, indexPattern) || '',
    ].filter(Boolean),

This snippet of code was returning an empty array.
In the dimension_editor the return value of that method was used to determine whether the field had an error or not:

kibana/x-pack/plugins/lens/public/indexpattern_datasource/dimension_panel/dimension_editor.tsx

Line 333 in 0cfd04c

const fieldErrorMessage =

Because of the truthiness of the empty array transitioning to Top Values was always showing an error in the UI.

[dej611]

getErrorMessage: (layer, columnId, indexPattern) =>
    [
      ...(getInvalidFieldMessage(
        layer.columns[columnId] as FieldBasedIndexPatternColumn,
        indexPattern
      ) || []),
      getDisallowedTermsMessage(layer, columnId, indexPattern) || '',
    ].filter(Boolean),

This snippet of code was returning an empty array.
In the dimension_editor the return value of that method was used to determine whether the field had an error or not:

kibana/x-pack/plugins/lens/public/indexpattern_datasource/dimension_panel/dimension_editor.tsx

Line 333 in 0cfd04c

const fieldErrorMessage =

Because of the truthiness of the empty array transitioning to Top Values was always showing an error in the UI.

Sorry wrong ref there, same name but different implementation.
The getErrorMessage was called within the canTransition function here:

kibana/x-pack/plugins/lens/public/indexpattern_datasource/dimension_panel/dimension_editor.tsx

Line 175 in 0cfd04c

compatibleWithCurrentField: canTransition({

[flash1293]

Got it, thanks. Could we adjust that place instead and do

!newDefinition.getErrorMessage?.(newLayer, columnId, indexPattern)?.length

In a bunch of other places we already treat empty array as no error, I think we should do the same here

[dej611]

I've added a check for the array length as well.
Ideally the getErrorMessage should return undefined on errors, and all of them but date_histogram do now. The length check is meant to be a fallback.

If you think that should be the only fix let me know.

[flash1293]

LGTM, didn't test again

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 6b5add5
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Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
lens	1.5MB	1.5MB	+175.0B

History

• 💚 Build #131785 succeeded 1b9f7e7

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[kibanamachine]

💚 Backport successful

Status	Branch	Result
✅	7.x

This backport PR will be merged automatically after passing CI.