Fix nightly feature

src/input.rs

@@ -69,9 +69,9 @@ impl<I: Iterator<Item = Result<char, CharsError>>> Iterator for Keys<I> {
             Some(Ok(c @ '\x01' ... '\x1A')) => Some(Key::Ctrl((c as u8 - 0x1  + b'a') as char)),
             Some(Ok(c @ '\x1C' ... '\x1F')) => Some(Key::Ctrl((c as u8 - 0x1C + b'4') as char)),
             None => None,
-            Some('\0') => Some(Key::Null),
+            Some(Ok('\0')) => Some(Key::Null),
             Some(Ok(c)) => Some(Key::Char(c)),
-            Some(Err(e)) => Some(Key::Error(e)),
+            Some(Err(e)) => Some(Key::Error(io::Error::new(io::ErrorKind::InvalidData, e))),
         }
     }
 }