fix: #4196

.changeset/big-humans-sleep.md

@@ -0,0 +1,5 @@
+---
+"@wagmi/core": patch
+---
+
+Made `serialize` and `deserialize` types more permissive.

packages/core/src/createStorage.test-d.ts

@@ -60,3 +60,15 @@ test('setItem', () => {
   // @ts-expect-error incorrect argument type
   storage.setItem('recentConnectorId', 1n)
 })
+
+test('serialize/deserialize types', () => {
+  createStorage({
+    deserialize(value) {
+      return value
+    },
+    serialize(value) {
+      return value
+    },
+    storage: localStorage,
+  })
+})

packages/core/src/createStorage.ts

@@ -41,9 +41,9 @@ export type BaseStorage = {
 }
 
 export type CreateStorageParameters = {
-  deserialize?: (<T>(value: string) => T) | undefined
+  deserialize?: (<type>(value: string) => type | unknown) | undefined
   key?: string | undefined
-  serialize?: (<T>(value: T) => string) | undefined
+  serialize?: (<type>(value: type | any) => string) | undefined
   storage?: Compute<BaseStorage> | undefined
 }