fix: JS should return an error if body is empty

[dobrac]

Fix error handling for API responses with empty body. Previously, when the API returned an error status code (4xx/5xx) with an empty response body, the error was not properly caught, causing a crash when accessing undefined response data. Now correctly detects errors by checking if error !== undefined instead of relying on truthiness check.

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Note

Low Risk
Small, localized change to client-side error detection plus new unit tests; main risk is slight behavior change for edge-case responses with falsy error values.

Overview
Fixes JS SDK API error detection for openapi-fetch responses where error bodies are empty (returned as ''), by treating response.error === undefined as the only “no error” case instead of using a truthiness check.

Adds a vitest suite for handleApiError covering empty-string error bodies across 4xx/5xx and special handling for 401/429, plus success cases, and includes a patch changeset entry.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 6aee2b8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
e2b	Patch

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