Make error an enum.

src/error.rs

@@ -0,0 +1,36 @@
+//
+// Copyright 2023 James Pace
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+//
+// This Source Code Form is "Incompatible With Secondary Licenses", as
+// defined by the Mozilla Public License, v. 2.0.
+//
+use alloc::string::{String, ToString};
+
+#[derive(Debug, Clone)]
+pub enum Error {
+    Msg(String),
+}
+
+impl Error {
+    pub fn from_msg(msg: &str) -> Self {
+        Error::Msg(msg.to_string())
+    }
+}
+
+impl core::fmt::Display for Error {
+    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
+        match self {
+            Error::Msg(msg) => {
+                write!(f, "Error manipulating graph: {}", msg)
+            }
+        }
+    }
+}
+
+impl core::error::Error for Error {}
+
+pub type Result<T, E = Error> = core::result::Result<T, E>;