🔒 Fix unhandled JSON.parse in Redux DevTools subscriber

src/Squawk.ts

@@ -131,8 +131,12 @@ export default function createStore<T>(initialState: Required<T>, useReduxDevToo
       // If Redux dev tools emitted a dispatch, and the state has a value
       if (message.type === "DISPATCH" && message.state) {
         // Deserialize the value and dispatch updates to all subscribers
-        globalState.set(JSON.parse(message.state));
-        notifySubscribers(globalState.keys());
+        try {
+          globalState.set(JSON.parse(message.state));
+          notifySubscribers(globalState.keys());
+        } catch {
+          // Ignore malformed JSON
+        }
       }
     });
   }

src/__tests__/Squawk.redux.test.ts

@@ -0,0 +1,33 @@
+import createStore from "../Squawk";
+
+describe("Redux DevTools integration", () => {
+  it("handles malformed JSON gracefully", () => {
+    const devToolsSubscribeCallbacks: Array<(msg: { type: string; state: string }) => void> = [];
+    // eslint-disable-next-line immutable/no-mutation, @typescript-eslint/no-explicit-any
+    (global as any).window = {
+      __REDUX_DEVTOOLS_EXTENSION__: {
+        connect: () => ({
+          subscribe: (cb: (msg: { type: string; state: string }) => void) => {
+            devToolsSubscribeCallbacks.push(cb);
+          },
+          // eslint-disable-next-line @typescript-eslint/no-empty-function
+          send: () => {},
+          // eslint-disable-next-line @typescript-eslint/no-empty-function
+          init: () => {}
+        })
+      }
+    };
+
+    const store = createStore({ foo: "bar" }, true);
+
+    expect(() => {
+      devToolsSubscribeCallbacks[0]({ type: "DISPATCH", state: "invalid json" });
+    }).not.toThrow();
+
+    expect(store.get().foo).toBe("bar");
+
+    // clean up
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    delete (global as any).window;
+  });
+});