move error handler to a separate module

src/error.rs

@@ -0,0 +1,50 @@
+#[derive(Debug)]
+pub struct Error {
+    message: String,
+}
+
+pub fn s2e(s: &str) -> Error {
+    Error::from(s)
+}
+
+impl From<std::io::Error> for Error {
+    fn from(err: std::io::Error) -> Self {
+        Self {
+            message: err.to_string(),
+        }
+    }
+}
+
+impl From<&str> for Error {
+    fn from(err: &str) -> Self {
+        Self {
+            message: err.to_string(),
+        }
+    }
+}
+
+impl From<String> for Error {
+    fn from(err: String) -> Self {
+        Self { message: err }
+    }
+}
+
+impl From<&String> for Error {
+    fn from(err: &String) -> Self {
+        Self {
+            message: err.to_string(),
+        }
+    }
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "{}", self.message)
+    }
+}
+
+impl std::error::Error for Error {
+    fn description(&self) -> &str {
+        &self.message
+    }
+}