fix #1022

src/basic/result-error/result.md

@@ -202,7 +202,7 @@ use std::io::Read;
 fn read_username_from_file() -> Result<String, io::Error> {
     let mut f = File::open("hello.txt")?;
     let mut s = String::new();
-    f.read_to_string(&mut s)?;
+    f?.read_to_string(&mut s)?;
     Ok(s)
 }
 ```