feat: better error message when flag key is not found in the project

[wichopy]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

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Describe the solution you've provided

when using the CLI, its not clear that the error is the flag key does not match a key thats registered in the project. The error is just "not found"

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Additional context

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[mike-zorn]

Thanks for the submission! That makes sense that we should distinguish between the project missing and the flag missing. We've used error types to distinguish between 5xx & 4xx errors. As a result, the fmt.Errorf approach won't work. Instead we'll need to incorporate which kinds of things we didn't find in the custom error type and map that out in the API. Let me know if you wanna take that on. Otherwise, we can treat this as a feature request and implement it.

[wichopy]

Thanks for the submission! That makes sense that we should distinguish between the project missing and the flag missing. We've used error types to distinguish between 5xx & 4xx errors. As a result, the fmt.Errorf approach won't work. Instead we'll need to incorporate which kinds of things we didn't find in the custom error type and map that out in the API. Let me know if you wanna take that on. Otherwise, we can treat this as a feature request and implement it.

Could i please just make a feature request then. When I was looking at the code I didn't see anything to reveal error codes with this ErrNotFound error so thought just adding the context to the error would be enough.

Feel free to take over this PR or close

[mike-zorn]

Oh. Yeah. We actually have a bug in here where we're returning 500s when it should be a 400. I'll close this one and fix up the error handling.