From 6e79eaf7399170611bcbefda0082947b629f2693 Mon Sep 17 00:00:00 2001
From: Maciej Sawicki <humberd.dev@gmail.com>
Date: Wed, 30 Apr 2025 12:02:03 +0200
Subject: [PATCH] fix(core): reading resource value after reload in the error
 state (#61441)

When the resource is loading after reloading from the error state reading `Resource.value()` would return the default value instead of throwing an error.
This change prevents `Resource.hasValue()` from throwing an error in such a case.

PR Close #61441
---
 packages/core/src/resource/resource.ts       |  5 +++
 packages/core/test/resource/resource_spec.ts | 42 ++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/packages/core/src/resource/resource.ts b/packages/core/src/resource/resource.ts
index 6bb72d3289a..6ed4b3f14e6 100644
--- a/packages/core/src/resource/resource.ts
+++ b/packages/core/src/resource/resource.ts
@@ -187,6 +187,11 @@ export class ResourceImpl<T, R> extends BaseWritableResource<T> implements Resou
             return defaultValue;
           }
 
+          // Prevents `hasValue()` from throwing an error when a reload happened in the error state
+          if (this.state().status === 'loading' && this.error()) {
+            return defaultValue;
+          }
+
           if (!isResolved(streamValue)) {
             if (throwErrorsFromValue) {
               throw new ResourceValueError(this.error()!);
diff --git a/packages/core/test/resource/resource_spec.ts b/packages/core/test/resource/resource_spec.ts
index cf5080ceb07..dfb4a857cc4 100644
--- a/packages/core/test/resource/resource_spec.ts
+++ b/packages/core/test/resource/resource_spec.ts
@@ -835,6 +835,48 @@ describe('resource', () => {
     expect(echoResource.error()).toBe(undefined);
     expect(aborted).toEqual([{counter: 0}, {counter: 0}]);
   });
+
+  it('should return default value when getting a value after reloading in the error state', async () => {
+    const backend = new MockEchoBackend();
+    const requestParam = {};
+    const echoResource = resource({
+      params: () => requestParam,
+      loader: (params) => backend.fetch(params.params),
+      injector: TestBed.inject(Injector),
+      defaultValue: 'my-default-value',
+    });
+
+    TestBed.tick();
+    await backend.reject(requestParam, new Error('Something went wrong....'));
+
+    expect(echoResource.status()).toBe('error');
+    expect(echoResource.isLoading()).toBeFalse();
+    expect(echoResource.hasValue()).toBeFalse();
+
+    const errFromValue = extractError(() => echoResource.value())!;
+    expect(errFromValue.message).toContain('Resource');
+    expect(errFromValue.message).toContain('Something went wrong....');
+    expect(errFromValue.cause).toEqual(new Error('Something went wrong....'));
+    expect(echoResource.error()!).toEqual(new Error('Something went wrong....'));
+
+    echoResource.reload();
+    TestBed.tick();
+
+    expect(echoResource.status()).toBe('reloading');
+    expect(echoResource.isLoading()).toBeTrue();
+    expect(echoResource.hasValue()).toBeTrue();
+    expect(echoResource.value()).toEqual('my-default-value');
+    expect(echoResource.error()).toEqual(new Error('Something went wrong....'));
+
+    await backend.flush();
+    TestBed.tick();
+
+    expect(echoResource.status()).toBe('resolved');
+    expect(echoResource.isLoading()).toBeFalse();
+    expect(echoResource.hasValue()).toBeTrue();
+    expect(echoResource.value()).toEqual({});
+    expect(echoResource.error()).toEqual(undefined);
+  });
 });
 
 function flushMicrotasks(): Promise<void> {