adding wrong input type handling. finished.

projects/guessing_game/src/main.rs

@@ -17,7 +17,10 @@ fn main() {
 
         let guess: u32 = match guess.trim().parse() {
             Ok(num) => num,
-            Err(_) => continue,
+            Err(_) => {
+                println!("Please input an integer!\n");
+                continue;
+            }
         };
 
         println!("You guessed : {}", guess);