handle show null data in JsonViewer

[kreazyme]

Fixes #9429

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• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
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[elliette]

Hello! Please sign the CLA and include an issue link in your PR description. Thank you!

[kreazyme]

Hi @elliette , thank for your review
I signed CLA, and here are issue link
#9429

[elliette]

Thank you! Change looks good. But it doesn't look like the CLA has been signed yet. Thanks!

[kreazyme]

Hi @elliette , I already signed to CLA, can you re-run the check CLA action ?

[srawlins]

This looks good to me. Can you provide an example request string that hits this crash?

[kreazyme]

Thank @srawlins for review my PR.
This issue happen when I try to patch null data with dio. That may occurs with other network library.

[kreazyme]

Hi @elliette,
Please take your time and review my PR.
Thanks.