don't throw runtime error when stdin closes

examples/hello_world.rs

@@ -7,10 +7,6 @@ fn main() {
         )
     );
     if eval.is_err() {
-        let err = eval.unwrap_err();
-        if err == "Stdin closed" {
-            return
-        }
-        eprintln!("Program failed: {}", err);
+        eprintln!("Program failed: \n{}", eval.unwrap_err());
     }
 }

src/lib.rs

@@ -119,7 +119,7 @@ pub fn eval_mem(bf_str: &&str, mem: &mut [u8], pointer: &mut usize) -> Result<()
         if char == ',' {
             let byte = stdin().bytes().next();
             if byte.is_none() {
-                return Err("Stdin closed".into());
+                continue
             }
             let byte = byte.unwrap();
             if byte.is_err() {