fix(client): Handle empty JSON responses

[sentry]

This PR addresses the issue "Error: Failed to parse JSON response: Unexpected end of JSON input" occurring in SentryApiService.parseJsonResponse.

Root Cause:
The parseJsonResponse method in packages/mcp-core/src/api-client/client.ts directly calls response.json() without checking if the response body is empty. This leads to an Unexpected end of JSON input error when Sentry API endpoints return a 200 or 204 status with no content, or when Cloudflare's fetch layer delivers an empty body.

Solution:
Modified parseJsonResponse to first read the response body as text. If the trimmed text content is empty, it now returns null, effectively bypassing the JSON parsing attempt for empty responses. For non-empty responses, it proceeds to parse the text as JSON within the existing error handling block. This prevents the parsing error while maintaining correct behavior for valid JSON and appropriate error reporting for malformed non-empty responses.

Fixes MCP-SERVER-FY2

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Null return breaks caller contracts

Medium Severity

parseJsonResponse now returns null for empty bodies, but every requestJSON caller still treats the result as required response data. Untyped call sites cast and read fields immediately, so empty responses become TypeErrors instead of the previous parse failure. Zod-backed call sites fail later with schema errors. Endpoints that intentionally return no body already go through request, not requestJSON.

 

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