otelhttp: nil check wrappedBody.Close (#2164)

* otelhttp: nil check wrappedBody.Close

* Update instrumentation/net/http/otelhttp/transport_test.go

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

CHANGELOG.md

@@ -22,6 +22,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Upgraded all dependencies on stable modules from `go.opentelemetry.io/otel` from v1.5.0 to v1.6.1. (#2134)
 - Upgraded all dependencies on metric modules from `go.opentelemetry.io/otel` from v0.27.0 to v0.28.0. (#1977)
 
+### Fixed
+
+- otelhttp: Avoid panic by adding nil check to `wrappedBody.Close` (#2164)
+
 ## [1.5.0/0.30.0/0.1.0] - 2022-03-16
 
 ### Added

instrumentation/net/http/otelhttp/transport.go

@@ -186,5 +186,8 @@ func (wb *wrappedBody) Read(b []byte) (int, error) {
 
 func (wb *wrappedBody) Close() error {
 	wb.span.End()
-	return wb.body.Close()
+	if wb.body != nil {
+		return wb.body.Close()
+	}
+	return nil
 }

instrumentation/net/http/otelhttp/transport_test.go

@@ -281,6 +281,13 @@ func TestWrappedBodyClose(t *testing.T) {
 	s.assert(t, true, nil, codes.Unset, "")
 }
 
+func TestWrappedBodyClosePanic(t *testing.T) {
+	s := new(span)
+	var body io.ReadCloser
+	wb := newWrappedBody(s, body)
+	assert.NotPanics(t, func() { wb.Close() }, "nil body should not panic on close")
+}
+
 func TestWrappedBodyCloseError(t *testing.T) {
 	s := new(span)
 	expectedErr := errors.New("test")