feat!: rewrite Graph internals

Use js class, static methods and protected methods for recurring functions.

Author: JesusTheHun

src/CycleError.ts

@@ -0,0 +1,6 @@
+export class CycleError extends Error {
+  constructor(message: string) {
+    super(message);
+    Object.setPrototypeOf(this, CycleError.prototype);
+  }
+}