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

app/brand.go

@@ -36,7 +36,9 @@ func (a *App) SaveBrandImage(imageData *multipart.FileHeader) *model.AppError {
 	config, _, err := image.DecodeConfig(file)
 	if err != nil {
 		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.decode_config.app_error", nil, err.Error(), http.StatusBadRequest)
-	} else if config.Width*config.Height > model.MaxImageSize {
+	}
+
+	if config.Width*config.Height > model.MaxImageSize {
 		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.too_large.app_error", nil, err.Error(), http.StatusBadRequest)
 	}