move contents of taskchampion repo to tc/

rust/taskchampion/src/errors.rs

@@ -0,0 +1,15 @@
+use thiserror::Error;
+
+#[derive(Debug, Error, Eq, PartialEq, Clone)]
+#[non_exhaustive]
+/// Errors returned from taskchampion operations
+pub enum Error {
+    /// A task-database-related error
+    #[error("Task Database Error: {0}")]
+    Database(String),
+    /// An error specifically indicating that the local replica cannot
+    /// be synchronized with the sever, due to being out of date or some
+    /// other irrecoverable error.
+    #[error("Local replica is out of sync with the server")]
+    OutOfSync,
+}