Fix an error in TableArtifactViewer when keys have an empty string

[nabenabe0928]

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This repository (optuna-dashboard) and Goptuna share common code.
This pull request may therefore be ported to Goptuna.
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Reference Issues/PRs

This issue relates to

• CSV ArtifactViewer whites out when clicking a square #911

What does this implement/fix? Explain your changes.

In my implementation, I replaced an empty string in keys with " ", which circumvents the error.

[c-bata]

@nabenabe0928 Thank you for your pull request! The changes look good, but the cause of issue #911 appears to be that Papa.parse() does not skip empty lines by default, leading to the result shown below:

Could you pass the skipEmptyLines: true option to Papa.parse()?

$ git diff
diff --git a/optuna_dashboard/ts/components/Artifact/TableArtifactViewer.tsx b/optuna_dashboard/ts/components/Artifact/TableArtifactViewer.tsx
index a9a2414..644dbff 100644
--- a/optuna_dashboard/ts/components/Artifact/TableArtifactViewer.tsx
+++ b/optuna_dashboard/ts/components/Artifact/TableArtifactViewer.tsx
@@ -143,6 +143,7 @@ const loadCSV = (props: TableArtifactViewerProps): Promise<Data[]> => {
     Papa.parse(props.src, {
       header: true,
       download: true,
+      skipEmptyLines: true,
       complete: (results: Papa.ParseResult<Data>) => {
         resolve(results?.data)
       },

https://www.papaparse.com/docs

[nabenabe0928]

@c-bata I tried your modification, but did not work (still whites out...)

[c-bata]

@nabenabe0928 Hmm... Could you please try the hard refresh? The patch seems to work fine on my environment actually.

[nabenabe0928]

I tried ctrl+f5 and the source is updated as highlighted.
However, I still get the same error, but I do not know why.
It could be a linux-related issue:(

[c-bata]

Thank you for your efforts to reproduce! It appears I misunderstood the cause of issue #911. Without the changes made in this PR, I also encountered the error you ran into.

Regarding the patch I suggested, it should be applied. However, it can be addressed in a follow-up. LGTM.