Refactor errors into separate file

Author: sjsyrek

source/error.js

@@ -0,0 +1,22 @@
+/**
+ * lazy-linked-lists
+ * Lazy and infinite linked lists for JavaScript.
+ *
+ * source/error.js
+ *
+ * Errors.
+ * @license ISC
+ */
+
+export class EmptyListError extends Error {
+  constructor(message) {
+    super(message);
+    this.name = 'EmptyListError';
+  }
+}
+export class OutOfRangeError extends Error {
+  constructor(message) {
+    super(message);
+    this.name = 'OutOfRangeError';
+  }
+}