simplify unmarshal (sashabaranov#191)

* simplify unmarshal

* simplify unmarshalError

* rename errorAccumulate -> defaultErrorAccumulator

* update converage

error_accumulator.go

@@ -8,7 +8,7 @@ import (
 
 type errorAccumulator interface {
 	write(p []byte) error
-	unmarshalError() (*ErrorResponse, error)
+	unmarshalError() *ErrorResponse
 }
 
 type errorBuffer interface {
@@ -17,35 +17,35 @@ type errorBuffer interface {
 	Bytes() []byte
 }
 
-type errorAccumulate struct {
+type defaultErrorAccumulator struct {
 	buffer      errorBuffer
 	unmarshaler unmarshaler
 }
 
 func newErrorAccumulator() errorAccumulator {
-	return &errorAccumulate{
+	return &defaultErrorAccumulator{
 		buffer:      &bytes.Buffer{},
 		unmarshaler: &jsonUnmarshaler{},
 	}
 }
 
-func (e *errorAccumulate) write(p []byte) error {
+func (e *defaultErrorAccumulator) write(p []byte) error {
 	_, err := e.buffer.Write(p)
 	if err != nil {
 		return fmt.Errorf("error accumulator write error, %w", err)
 	}
 	return nil
 }
 
-func (e *errorAccumulate) unmarshalError() (*ErrorResponse, error) {
-	var err error
-	if e.buffer.Len() > 0 {
-		var errRes ErrorResponse
-		err = e.unmarshaler.unmarshal(e.buffer.Bytes(), &errRes)
-		if err != nil {
-			return nil, err
-		}
-		return &errRes, nil
+func (e *defaultErrorAccumulator) unmarshalError() (errResp *ErrorResponse) {
+	if e.buffer.Len() == 0 {
+		return
 	}
-	return nil, err
+
+	err := e.unmarshaler.unmarshal(e.buffer.Bytes(), &errResp)
+	if err != nil {
+		errResp = nil
+	}
+
+	return
 }

error_accumulator_test.go

@@ -36,23 +36,29 @@ func (*failingUnMarshaller) unmarshal(_ []byte, _ any) error {
 }
 
 func TestErrorAccumulatorReturnsUnmarshalerErrors(t *testing.T) {
-	accumulator := &errorAccumulate{
+	accumulator := &defaultErrorAccumulator{
 		buffer:      &bytes.Buffer{},
 		unmarshaler: &failingUnMarshaller{},
 	}
 
+	respErr := accumulator.unmarshalError()
+	if respErr != nil {
+		t.Fatalf("Did not return nil with empty buffer: %v", respErr)
+	}
+
 	err := accumulator.write([]byte("{"))
 	if err != nil {
 		t.Fatalf("%+v", err)
 	}
-	_, err = accumulator.unmarshalError()
-	if !errors.Is(err, errTestUnmarshalerFailed) {
-		t.Fatalf("Did not return error when unmarshaler failed: %v", err)
+
+	respErr = accumulator.unmarshalError()
+	if respErr != nil {
+		t.Fatalf("Did not return nil when unmarshaler failed: %v", respErr)
 	}
 }
 
 func TestErrorByteWriteErrors(t *testing.T) {
-	accumulator := &errorAccumulate{
+	accumulator := &defaultErrorAccumulator{
 		buffer:      &failingErrorBuffer{},
 		unmarshaler: &jsonUnmarshaler{},
 	}
@@ -78,7 +84,7 @@ func TestErrorAccumulatorWriteErrors(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	stream.errAccumulator = &errorAccumulate{
+	stream.errAccumulator = &defaultErrorAccumulator{
 		buffer:      &failingErrorBuffer{},
 		unmarshaler: &jsonUnmarshaler{},
 	}

stream_reader.go

@@ -33,8 +33,9 @@ func (stream *streamReader[T]) Recv() (response T, err error) {
 waitForData:
 	line, err := stream.reader.ReadBytes('\n')
 	if err != nil {
-		if errRes, _ := stream.errAccumulator.unmarshalError(); errRes != nil {
-			err = fmt.Errorf("error, %w", errRes.Error)
+		respErr := stream.errAccumulator.unmarshalError()
+		if respErr != nil {
+			err = fmt.Errorf("error, %w", respErr.Error)
 		}
 		return
 	}