Migrate to idiomatic error handling app/a*.go and app/b*.go (#9455)

app/admin.go

@@ -238,14 +238,15 @@ func (a *App) TestEmail(userId string, cfg *model.Config) *model.AppError {
 			return model.NewAppError("testEmail", "api.admin.test_email.reenter_password", nil, "", http.StatusBadRequest)
 		}
 	}
-	if user, err := a.GetUser(userId); err != nil {
+	user, err := a.GetUser(userId)
+	if err != nil {
 		return err
-	} else {
-		T := utils.GetUserTranslations(user.Locale)
-		license := a.License()
-		if err := mailservice.SendMailUsingConfig(user.Email, T("api.admin.test_email.subject"), T("api.admin.test_email.body"), cfg, license != nil && *license.Features.Compliance); err != nil {
-			return model.NewAppError("testEmail", "app.admin.test_email.failure", map[string]interface{}{"Error": err.Error()}, "", http.StatusInternalServerError)
-		}
+	}
+
+	T := utils.GetUserTranslations(user.Locale)
+	license := a.License()
+	if err := mailservice.SendMailUsingConfig(user.Email, T("api.admin.test_email.subject"), T("api.admin.test_email.body"), cfg, license != nil && *license.Features.Compliance); err != nil {
+		return model.NewAppError("testEmail", "app.admin.test_email.failure", map[string]interface{}{"Error": err.Error()}, "", http.StatusInternalServerError)
 	}
 
 	return nil