Added NotFoundError and EmptyError

hw9/task1/src/lib.rs

             match str.next() {
                 Some("STAGE") => {
                     let msg = m[6..].trim_left();
-
-                    /* let mut msg = String::new();
-                    while let Some(sub_msg) = s.next() {
-                        msg += " ";
-                        msg += sub_msg
-                    }*/
                     Command::Stage(msg.to_string())
                 }
                 Some("CONTROL") => {
                     let cmd = m[8..].trim_left();
-
-                    /*let mut cmd = String::new();
-                    while let Some(sub_cmd) = s.next() {
-                        cmd += " ";
-                        cmd += sub_cmd
-                    }*/
                     Command::Control(cmd.to_string())
                 }
-                Some("RETRIEVE") => {
-                    Command::Retrieve
-                }
-                Some(_) => {
-                    Command::Error
-                }
-                None => panic!("Parse Error")
+                Some("RETRIEVE") => { Command::Retrieve }
+                Some(_) => { Command::NotFoundError }
+                None => { Command::EmptyError }
             }
         }
-        None => panic!("Parse Error!")
+        None => { Command::EmptyError }
     }
 }
 
     Stage(String),
     Control(String),
     Retrieve,
-    Error,
+    NotFoundError,
+    EmptyError,
 }