fix(signals): revert the protection for state mutation in dev mode (#4686)

Closes #4683

Author: rainerhahnekamp

modules/signals/spec/deep-freeze.spec.ts

@@ -1,15 +1,14 @@
 import { signal } from '@angular/core';
 import { STATE_SOURCE, WritableStateSource } from './state-source';
 import { DeepSignal, toDeepSignal } from './deep-signal';
-import { freezeInDevMode } from './deep-freeze';
 
 export type SignalState<State extends object> = DeepSignal<State> &
   WritableStateSource<State>;
 
 export function signalState<State extends object>(
   initialState: State
 ): SignalState<State> {
-  const stateSource = signal(freezeInDevMode(initialState as State));
+  const stateSource = signal(initialState as State);
   const signalState = toDeepSignal(stateSource.asReadonly());
   Object.defineProperty(signalState, STATE_SOURCE, {
     value: stateSource,

modules/signals/src/deep-freeze.ts

@@ -8,7 +8,6 @@ import {
   WritableSignal,
 } from '@angular/core';
 import { Prettify } from './ts-helpers';
-import { freezeInDevMode } from './deep-freeze';
 
 const STATE_WATCHERS = new WeakMap<Signal<object>, Array<StateWatcher<any>>>();
 
@@ -38,11 +37,10 @@ export function patchState<State extends object>(
 ): void {
   stateSource[STATE_SOURCE].update((currentState) =>
     updaters.reduce(
-      (nextState: State, updater) =>
-        freezeInDevMode({
-          ...nextState,
-          ...(typeof updater === 'function' ? updater(nextState) : updater),
-        }),
+      (nextState: State, updater) => ({
+        ...nextState,
+        ...(typeof updater === 'function' ? updater(nextState) : updater),
+      }),
       currentState
     )
   );

modules/signals/src/signal-state.ts

@@ -9,7 +9,6 @@ import {
   SignalStoreFeature,
   SignalStoreFeatureResult,
 } from './signal-store-models';
-import { freezeInDevMode } from './deep-freeze';
 
 export function withState<State extends object>(
   stateFactory: () => State
@@ -36,12 +35,10 @@ export function withState<State extends object>(
 
     assertUniqueStoreMembers(store, stateKeys);
 
-    store[STATE_SOURCE].update((currentState) =>
-      freezeInDevMode({
-        ...currentState,
-        ...state,
-      })
-    );
+    store[STATE_SOURCE].update((currentState) => ({
+      ...currentState,
+      ...state,
+    }));
 
     const stateSignals = stateKeys.reduce((acc, key) => {
       const sliceSignal = computed(

modules/signals/src/state-source.ts

@@ -23,49 +23,6 @@ Version 19 has the minimum version requirements:
 
 ### Signals
 
-#### Throw error in dev mode on state mutation
-
-The `patchState` method applies a deep freeze on the state in dev mode.
-If you try to update the state directly, it will throw an error in dev mode.
-
-BEFORE:
-
-```ts
-const userState = signalState(initialState);
-patchState(userState, (state) => {
-  // mutable change which went through
-  state.user.firstName = 'mutable change';
-  return state;
-});
-```
-
-AFTER:
-
-```ts
-const userState = signalState(initialState);
-patchState(userState, (state) => {
-  // mutable change throws in dev mode
-  state.user.firstName = 'mutable change'; 
-  return state;
-});
-```
-
-To fix the error, update the state in an immutable way.
-
-```ts
-const userState = signalState(initialState);
-patchState(userState, (state) => {
-  return {
-    ...state,
-    user: {
-      ...state.user,
-      // immutable change which went through
-      firstName: 'immutable change', 
-    },
-  };
-});
-```
-
 #### `computed` is replaced with `props`
 
 To support more cases, the `props` property is added to  `signalStoreFeature`, which replaces the existing `computed` property.

modules/signals/src/with-state.ts

@@ -87,7 +87,6 @@ patchState(
 <div class="alert is-critical">
 
 Updaters passed to the `patchState` function must perform state updates in an immutable manner.
-If a mutable change occurs to the state object, an error will be thrown in development mode.
 
 </div>