Introduce 'Error' enum

src/error.rs

@@ -0,0 +1,16 @@
+/// A singular type for all errors that could happen when using this library.
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Error {
+    InvalidFen,
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let error_msg = match self {
+            Self::InvalidFen => "Invalid FEN input",
+        };
+        write!(f, "{}", error_msg)
+    }
+}
+
+impl std::error::Error for Error {}

src/lib.rs

@@ -1,3 +1,4 @@
 pub mod board;
+pub mod error;
 pub mod movegen;
 pub mod utils;