Standardize fetch API

[elliottlawrence]

Pull Request Checklist

• Target branch: Pull requests should target the dev branch.
• Description: Briefly describe the changes in this pull request.
• Changelog: Ensure a changelog entry following the format of Keep a Changelog is added at the bottom of the PR description.
• Documentation: Have you updated relevant documentation Open WebUI Docs, or other documentation sources?
• Dependencies: Are there any new dependencies? Have you updated the dependency versions in the documentation?
• Testing: Have you written and run sufficient tests for the changes?
• Code Review: Have you self-reviewed your code and addressed any coding standard issues?

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Description

There are quite a few places in the frontend code that use a similar pattern of calling fetch() and then dealing with error handling. This should probably be standardized with a helper function.

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Changelog Entry

Added

Fixed

Changed

• Refactored fetch calls to have standardized error handling

Removed

Security

Breaking Changes

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Additional Information

I tried to be somewhat cautious about changing existing callsites of fetch. Most of them follow the same pattern but some are slightly different and I left those as-is. I figured this would be a good start and the rest can be cleaned up later.

I did a sanity check that the UI still seems to work, but there are quite a few changes here so I haven't tested every API call.

[elliottlawrence]

This is where I added the new helper function.

[elliottlawrence]

@tjbck - Any reason this PR was closed?