fix: ignore circular references when checking serializable

packages/core/src/__tests__/isSerializable.test.tsx

@@ -0,0 +1,70 @@
+import isSerializable from '../isSerializable';
+
+it('returns true for serializable object', () => {
+  expect(
+    isSerializable({
+      index: 0,
+      key: '7',
+      routeNames: ['foo', 'bar'],
+      routes: [
+        {
+          key: 'foo',
+          name: 'foo',
+          state: {
+            index: 0,
+            key: '8',
+            routeNames: ['qux', 'lex'],
+            routes: [
+              { key: 'qux', name: 'qux' },
+              { key: 'lex', name: 'lex' },
+            ],
+          },
+        },
+      ],
+    })
+  ).toBe(true);
+});
+
+it('returns false for non-serializable object', () => {
+  expect(
+    isSerializable({
+      index: 0,
+      key: '7',
+      routeNames: ['foo', 'bar'],
+      routes: [
+        {
+          key: 'foo',
+          name: 'foo',
+          state: {
+            index: 0,
+            key: '8',
+            routeNames: ['qux', 'lex'],
+            routes: [
+              { key: 'qux', name: 'qux', params: () => 42 },
+              { key: 'lex', name: 'lex' },
+            ],
+          },
+        },
+      ],
+    })
+  ).toBe(false);
+});
+
+it('returns false for circular references', () => {
+  const o = {
+    index: 0,
+    key: '7',
+    routeNames: ['foo', 'bar'],
+    routes: [
+      {
+        key: 'foo',
+        name: 'foo',
+      },
+    ],
+  };
+
+  // @ts-ignore
+  o.routes[0].state = o;
+
+  expect(isSerializable(o)).toBe(false);
+});

packages/core/src/isSerializable.tsx

@@ -1,4 +1,7 @@
-export default function isSerializable(o: { [key: string]: any }): boolean {
+const isSerializableWithoutCircularReference = (
+  o: { [key: string]: any },
+  seen = new Set<any>()
+): boolean => {
   if (
     o === undefined ||
     o === null ||
@@ -16,19 +19,29 @@ export default function isSerializable(o: { [key: string]: any }): boolean {
     return false;
   }
 
+  if (seen.has(o)) {
+    return false;
+  }
+
+  seen.add(o);
+
   if (Array.isArray(o)) {
     for (const it of o) {
-      if (!isSerializable(it)) {
+      if (!isSerializableWithoutCircularReference(it, seen)) {
         return false;
       }
     }
   } else {
     for (const key in o) {
-      if (!isSerializable(o[key])) {
+      if (!isSerializableWithoutCircularReference(o[key], seen)) {
         return false;
       }
     }
   }
 
   return true;
+};
+
+export default function isSerializable(o: { [key: string]: any }) {
+  return isSerializableWithoutCircularReference(o);
 }