Create image folder if it does not exist

internal/fileutils/fileutils.go

@@ -96,3 +96,14 @@ func computePathFromName(ac *appcontext.AppContext, filename string) string {
 func GetWsLinkPrefix() string {
 	return "/static/bookcover/"
 }
+
+func CreateFolderIfMissing(dir string) error {
+	_, openFileErr := os.Open(dir)
+	if os.IsNotExist(openFileErr) {
+		return os.MkdirAll(dir, 0755)
+	} else if openFileErr != nil {
+		return openFileErr
+	} else {
+		return nil
+	}
+}