Style fixes to tor-bytes errors.

Also note an issue with the design of tor-bytes::Error that should
probably go in a separate MR.

crates/tor-bytes/src/err.rs

@@ -3,6 +3,10 @@
 use thiserror::Error;
 
 /// Error type for decoding and encoding Tor objects from and to bytes.
+//
+// TODO(nickm): This error type could use a redesign: it doesn't do a good job
+// of preserving context.  At the least it should say what kind of object it
+// found any given problem in.
 #[derive(Error, Debug, Clone)]
 #[non_exhaustive]
 pub enum Error {
@@ -11,23 +15,23 @@ pub enum Error {
     /// This can mean that the object is truncated, or that we need to
     /// read more and try again, depending on the context in which it
     /// was received.
-    #[error("object truncated (or not fully present)")]
+    #[error("Object truncated (or not fully present)")]
     Truncated,
     /// Called Reader::should_be_exhausted(), but found bytes anyway.
-    #[error("extra bytes at end of object")]
+    #[error("Extra bytes at end of object")]
     ExtraneousBytes,
     /// Invalid length value (eg, overflow)
-    #[error("bad length value")]
+    #[error("Object length out of bounds")]
     BadLengthValue,
     /// An attempt to parse an object failed for some reason related to its
     /// contents.
-    #[error("bad object: {0}")]
+    #[error("Bad object: {0}")]
     BadMessage(&'static str),
     /// A parsing error that should never happen.
     ///
     /// We use this one in lieu of calling assert() and expect() and
     /// unwrap() from within parsing code.
-    #[error("bug")]
+    #[error("Internal error")]
     Bug(#[from] tor_error::Bug),
 }