fix: claude can not handle empty string

[yihong0618]

Summary

This patch try to fix claude api can not handle empty string problem.
close #9366
close #10013
close #10520.

more: info -> we can check others face the problem

dspinellis/ai-cli-lib@0ddcaac
dspinellis/ai-cli-lib#16

karthink/gptel@8b129c5#diff-17f2ed0388d8bb8379b05dd47711d80f6b44463ff782876fc7084ae1df090fe6R97
karthink/gptel#409

as a refer that fix it.

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Close issue syntax: Fixes #<issue number> or Resolves #<issue number>, see documentation for more details.

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Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[crazywoola]

cc @laipz8200

[laipz8200]

Thanks.

Maybe we should add some validation logic in the PromptMessage model.

[yihong0618]

Thanks.

Maybe we should add some validation logic in the PromptMessage model.

did some search seems only claude had this problem for now, and I am not quite sure it fixed, waiting for the user reponse.