imageservice: Don't hide error in Extract functions

The following functions where returning a
decoded result and the error of the decoding
operation without checking if the original
result contains an error already:

  func (c CreateResult) Extract() (*Image, error)
  func (c GetResult) Extract() (*Image, error)
  func (u UpdateResult) Extract() (*Image, error)

Signed-off-by: Alberto Murillo <alberto.murillo.silva@intel.com>

Author: Alberto Murillo

openstack/imageservice/v2/images/results.go

@@ -73,6 +73,9 @@ type CreateResult struct {
 
 // Extract build CreateResults from imput Image
 func (c CreateResult) Extract() (*Image, error) {
+	if c.Err != nil {
+		return nil, c.Err
+	}
 	var image *Image
 
 	err := mapstructure.Decode(c.Result.Body, &image)
@@ -91,6 +94,9 @@ type GetResult struct {
 
 // Extract builds GetResult
 func (c GetResult) Extract() (*Image, error) {
+	if c.Err != nil {
+		return nil, c.Err
+	}
 	var image *Image
 
 	err := mapstructure.Decode(c.Result.Body, &image)
@@ -104,6 +110,9 @@ type UpdateResult struct {
 
 // Extract builds UpdateResult
 func (u UpdateResult) Extract() (*Image, error) {
+	if u.Err != nil {
+		return nil, u.Err
+	}
 	var image *Image
 
 	err := mapstructure.Decode(u.Result.Body, &image)