Start reading in indexed PNG file

src/Tools/tool_helper/src/lib.rs

@@ -49,6 +49,11 @@ impl Error {
     pub fn ok_or_new<T, F>(option: Option<T>, error_text: F) -> Result<T, Error> where F: Fn () -> String{
         Ok(option.ok_or(Error::from_callback(error_text))?)
     }
+
+    pub fn with_action(mut self, action: &str) -> Error {
+        self.action = action.to_owned();
+        self
+    }
 }
 
 impl std::fmt::Display for Error {