Summary

• reject additional top-level JSON values in jsonx unmarshalling
• preserve UseNumber behavior and allow trailing whitespace
• cover all three public unmarshal entry points with a regression test

Reproduction

Before this change, each jsonx unmarshal helper returned nil for input containing two top-level values, such as:

var value map[string]any
err := jsonx.Unmarshal([]byte(`{"first": 1} {"second": 2}`), &value)

The first object was decoded and the second was silently ignored. The added regression test failed before the production change with An error is expected but got nil.

Root cause

unmarshalUseNumber called json.Decoder.Decode only once. A decoder accepts a stream of JSON values, so a successful first decode does not prove that the input contains exactly one value.

Solution

After decoding the requested value, perform one more decode and require io.EOF. A second successful decode is reported as multiple JSON values, while malformed trailing data returns the decoder error.

Tests

• go test ./core/jsonx -count=1 — pass
• go vet ./core/jsonx — pass
• go test -race ./core/jsonx -count=1 — pass