refactor: return ErrNoSuchAPIID any time we get 422

pkg/pmapi/client.go

@@ -57,7 +57,7 @@ var (
 	ErrAPINotReachable    = errors.New("cannot reach the server")
 	ErrUpgradeApplication = errors.New("application upgrade required")
 
-	ErrNoSuchMessage = errors.New("no such message")
+	ErrNoSuchAPIID = errors.New("no such API ID")
 )
 
 type ErrUnauthorized struct {

pkg/pmapi/messages.go

@@ -532,14 +532,7 @@ func (c *Client) GetMessage(id string) (msg *Message, err error) {
 		return
 	}
 
-	if res.StatusCode == http.StatusUnprocessableEntity {
-		err = ErrNoSuchMessage
-		return
-	}
-
-	msg, err = res.Message, res.Err()
-
-	return
+	return res.Message, res.Err()
 }
 
 type SendMessageReq struct {

pkg/pmapi/res.go

@@ -17,6 +17,8 @@
 
 package pmapi
 
+import "net/http"
+
 // Common response codes.
 const (
 	CodeOk = 1000
@@ -35,6 +37,10 @@ type Res struct {
 
 // Err returns error if the response is an error. Otherwise, returns nil.
 func (res Res) Err() error {
+	if res.StatusCode == http.StatusUnprocessableEntity {
+		return ErrNoSuchAPIID
+	}
+
 	if res.ResError == nil {
 		return nil
 	}