fix error handling when trying to open files

store.go

@@ -149,7 +149,9 @@ func ReadImage(filename string) (*bytes.Buffer, error) {
 
 func fileExists(filename string) bool {
 	info, err := os.Stat(filename)
-	if os.IsNotExist(err) {
+
+	if err != nil {
+		// return false on any error
 		return false
 	}