anomalyco
UI overlay breaks when Vertex AI returns truncated JSON responses
Description
When using OpenCode heavily with Vertex AI Flash models, the UI breaks with an error overlay showing:
SyntaxError: Unexpected end of JSON input
at <parse> (native)
at json (unknown)
at <anonymous> (../sdk/js/src/v2/gen/client/client.gen.ts:167:33)
Environment
- Provider: Vertex AI (Flash models)
- Usage pattern: Heavy/concurrent usage
Root Cause Analysis
The error occurs at client.gen.ts:167 when response.json() is called on a truncated response body. This happens when:
- Network connection drops mid-response
- Vertex AI times out or rate-limits under load
- Multiple concurrent requests strain the connection
While error handling exists in the SDK (lines 169-198), the error still surfaces to the UI and breaks the interface with an overlay.
Expected Behavior
Transient JSON parse errors from provider responses should be caught and retried gracefully without breaking the UI overlay.
Actual Behavior
Error overlay appears, blocking the UI and requiring manual dismissal or restart.
Screenshot
Suggested Fix
Consider catching SyntaxError specifically in the streaming/response handling layer and treating truncated JSON as a retryable error rather than surfacing it to the UI.
