Remove the unused "Error" type from caret.

This was a relic of the old, now-unused "caret_enum!" macro.
Removing it gets caret's coverage to 100%.

Yes, technically this is a semver breaker on caret.

crates/caret/src/lib.rs

@@ -67,30 +67,6 @@
 #![warn(clippy::unseparated_literal_suffix)]
 #![deny(clippy::unwrap_used)]
 
-/// An error produced from type derived from type.  These errors can
-/// only occur when trying to convert to a type made with caret_enum!
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[non_exhaustive]
-pub enum Error {
-    /// Tried to convert to an enumeration type from an integer that
-    /// didn't represent a member of that enumeration.
-    InvalidInteger,
-    /// Tried to convert to an enumeration type from a string that
-    /// didn't represent a member of that enumeration.
-    InvalidString,
-}
-
-impl std::fmt::Display for Error {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Error::InvalidInteger => write!(f, "Integer was not member of this enumeration"),
-            Error::InvalidString => write!(f, "String was not member of this enumeration"),
-        }
-    }
-}
-
-impl std::error::Error for Error {}
-
 /// Declare an integer type with some named elements.
 ///
 /// This macro declares a struct that wraps an integer

doc/semver_status.md

@@ -29,3 +29,6 @@ arti-client: MODIFIED
 
 tor-units: MODIFIED
   (Eq,PartialEq for BoundedInt32)
+
+caret: BREAKING
+  (Removed unused-but-exported Error type.)