fix(react-query): retry queries with falsy errors on mount

.changeset/fuzzy-rats-mutate.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/react-query': patch
+---
+
+Allow queries with falsy errors to retry on mount when `throwOnError` returns false.

packages/react-query/src/__tests__/useQuery.test.tsx

@@ -6802,6 +6802,35 @@ describe('useQuery', () => {
     expect(queryFn).toHaveBeenCalledTimes(2)
   })
 
+  it('should retry on mount when throwOnError returns false for a falsy error', async () => {
+    const key = queryKey()
+    const queryFn = vi.fn(() => Promise.reject())
+
+    function Component() {
+      const { status } = useQuery({
+        queryKey: key,
+        queryFn,
+        throwOnError: () => false,
+        retryOnMount: () => true,
+        staleTime: Infinity,
+        retry: false,
+      })
+
+      return <div data-testid="status">{status}</div>
+    }
+
+    const rendered1 = renderWithClient(queryClient, <Component />)
+    await vi.advanceTimersByTimeAsync(0)
+    expect(rendered1.getByTestId('status')).toHaveTextContent('error')
+    expect(queryFn).toHaveBeenCalledTimes(1)
+    rendered1.unmount()
+
+    const rendered2 = renderWithClient(queryClient, <Component />)
+    await vi.advanceTimersByTimeAsync(0)
+    expect(rendered2.getByTestId('status')).toHaveTextContent('error')
+    expect(queryFn).toHaveBeenCalledTimes(2)
+  })
+
   it('should not retry on mount when throwOnError function returns true', async () => {
     const key = queryKey()
     let fetchCount = 0

packages/react-query/src/errorBoundaryUtils.ts

@@ -27,10 +27,14 @@ export const ensurePreventErrorBoundaryRetry = <
   errorResetBoundary: QueryErrorResetBoundaryValue,
   query: Query<TQueryFnData, TError, TQueryData, TQueryKey> | undefined,
 ) => {
-  const throwOnError =
-    query?.state.error && typeof options.throwOnError === 'function'
-      ? shouldThrowError(options.throwOnError, [query.state.error, query])
-      : options.throwOnError
+  let throwOnError = options.throwOnError
+
+  if (query?.state.status === 'error' && typeof throwOnError === 'function') {
+    throwOnError = shouldThrowError(throwOnError, [
+      query.state.error as TError,
+      query,
+    ])
+  }
 
   if (options.suspense || throwOnError) {
     // Prevent retrying failed query if the error boundary has not been reset yet