The Send bound is an unnecessary restriction, and though provided as a
convenience, can't be removed by downstream code.
The removal of this bound is a [breaking-change] since it
removes an implicit Send bound on all `E: Error` and all
`Error` trait objects.
To migrate, consider if your code actually requires the Send
bound and, if so, add it explicitly.
Fixes #23774
/// Base functionality for all errors in Rust.
#[stable(feature = "rust1", since = "1.0.0")]
-pub trait Error: Debug + Display + Send {
+pub trait Error: Debug + Display {
/// A short description of the error.
///
/// The description should not contain newlines or sentence-ending