errors: fix FromError and errors.Unmarshal

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

errors/errors.go

@@ -84,9 +84,9 @@ func New(id, detail string, code int32) error {
 // Parse tries to parse a JSON string into an error. If that
 // fails, it will set the given string as the error detail.
 func Parse(err string) *Error {
-	e := new(Error)
-	errr := json.Unmarshal([]byte(err), e)
-	if errr != nil {
+	e := &Error{}
+	nerr := json.Unmarshal([]byte(err), e)
+	if nerr != nil {
 		e.Detail = err
 	}
 	return e
@@ -283,6 +283,10 @@ func (e *Error) Unmarshal(data []byte) error {
 			return r == ':'
 		})
 		for idx := 0; idx < len(nparts); idx++ {
+			if len(nparts[idx+1]) < 3 {
+				idx++
+				continue
+			}
 			switch {
 			case nparts[idx] == `"id"`:
 				e.ID = nparts[idx+1][1 : len(nparts[idx+1])-1]
@@ -297,6 +301,7 @@ func (e *Error) Unmarshal(data []byte) error {
 				}
 				e.Code = int32(c)
 			}
+			idx++
 		}
 	}
 	return nil

errors/errors_test.go

@@ -2,10 +2,24 @@ package errors
 
 import (
 	er "errors"
+	"fmt"
 	"net/http"
 	"testing"
 )
 
+func TestEmpty(t *testing.T) {
+	msg := "test"
+	var err *Error
+	err = FromError(fmt.Errorf(msg))
+	if err.Detail != msg {
+		t.Fatalf("invalid error %v", err)
+	}
+	err = FromError(fmt.Errorf(`{"id":"","detail":"%s","status":"%s","code":0}`, msg, msg))
+	if err.Detail != msg || err.Status != msg {
+		t.Fatalf("invalid error %#+v", err)
+	}
+}
+
 func TestFromError(t *testing.T) {
 	err := NotFound("go.micro.test", "%s", "example")
 	merr := FromError(err)