Add an error class

lexer/src/error.rs

@@ -0,0 +1,16 @@
+/* lexer/src/error.rs
+ * Eryn Wells <eryn@erynwells.me>
+ */
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct Error {
+    message: String
+}
+
+impl Error {
+    pub fn new(msg: String) -> Error {
+        Error {
+            message: msg
+        }
+    }
+}