fix(core): Prevents trying to trigger incremental hydration on CSR (#58366)

hydrate triggers were firing in CSR cases and attempting to find parent defer blocks. This prevents that from happening. In these cases, the defer block id will be empty.

fixes: #58359

PR Close #58366

packages/core/src/event_delegation_utils.ts

@@ -78,15 +78,17 @@ export const sharedMapFunction = (rEl: RElement, jsActionMap: Map<string, Set<El
 };
 
 export function removeListenersFromBlocks(blockNames: string[], injector: Injector) {
-  let blockList: Element[] = [];
-  const jsActionMap = injector.get(BLOCK_ELEMENT_MAP);
-  for (let blockName of blockNames) {
-    if (jsActionMap.has(blockName)) {
-      blockList = [...blockList, ...jsActionMap.get(blockName)!];
+  if (blockNames.length > 0) {
+    let blockList: Element[] = [];
+    const jsActionMap = injector.get(BLOCK_ELEMENT_MAP);
+    for (let blockName of blockNames) {
+      if (jsActionMap.has(blockName)) {
+        blockList = [...blockList, ...jsActionMap.get(blockName)!];
+      }
     }
+    const replayList = new Set(blockList);
+    replayList.forEach(removeListeners);
   }
-  const replayList = new Set(blockList);
-  replayList.forEach(removeListeners);
 }
 
 export const removeListeners = (el: Element) => {

packages/core/src/hydration/blocks.ts

@@ -62,6 +62,9 @@ export async function hydrateFromBlockName(
   deferBlock: DeferBlock | null;
   hydratedBlocks: Set<string>;
 }> {
+  if (blockName == null) {
+    return {deferBlock: null, hydratedBlocks};
+  }
   const deferBlockRegistry = injector.get(DeferBlockRegistry);
 
   // Make sure we don't hydrate/trigger the same thing multiple times
@@ -116,4 +119,5 @@ export async function incrementallyHydrateFromBlockName(
     // the hydration process has finished, which could result in problems
     await whenStable(injector.get(ApplicationRef));
   }
+  return Promise.resolve();
 }

packages/platform-server/test/incremental_hydration_spec.ts

@@ -18,11 +18,17 @@ import {
   ɵwhenStable as whenStable,
 } from '@angular/core';
 
-import {getAppContents, prepareEnvironmentAndHydrate, resetTViewsFor} from './dom_utils';
+import {getAppContents, hydrate, prepareEnvironmentAndHydrate, resetTViewsFor} from './dom_utils';
 import {getComponentRef, ssr, timeout} from './hydration_utils';
 import {getDocument} from '@angular/core/src/render3/interfaces/document';
 import {isPlatformServer} from '@angular/common';
-import {withEventReplay, withIncrementalHydration} from '@angular/platform-browser';
+import {
+  provideClientHydration,
+  withEventReplay,
+  withIncrementalHydration,
+} from '@angular/platform-browser';
+import {TestBed} from '@angular/core/testing';
+import {PLATFORM_BROWSER_ID} from '@angular/common/src/platform_id';
 
 describe('platform-server partial hydration integration', () => {
   const originalWindow = globalThis.window;
@@ -1393,6 +1399,47 @@ describe('platform-server partial hydration integration', () => {
     }, 100_000);
   });
 
+  describe('client side navigation', () => {
+    beforeEach(() => {
+      TestBed.configureTestingModule({
+        providers: [
+          {provide: PLATFORM_ID, useValue: PLATFORM_BROWSER_ID},
+          provideClientHydration(withIncrementalHydration()),
+        ],
+      });
+    });
+
+    it('should not try to hydrate in CSR only cases', async () => {
+      @Component({
+        standalone: true,
+        selector: 'app',
+        template: `
+          <main (click)="fnA()">
+            @defer (hydrate when true) {
+              <article>
+                defer block rendered!
+                <span id="test" (click)="fnB()">{{value()}}</span>
+              </article>
+            } @placeholder {
+              <span>Outer block placeholder</span>
+            }
+          </main>
+        `,
+      })
+      class SimpleComponent {
+        value = signal('start');
+        fnA() {}
+        fnB() {
+          this.value.set('end');
+        }
+      }
+      const fixture = TestBed.createComponent(SimpleComponent);
+      fixture.detectChanges();
+
+      expect(fixture.nativeElement.innerHTML).toContain('Outer block placeholder');
+    });
+  });
+
   describe('cleanup', () => {
     it('should cleanup partial hydration blocks appropriately', async () => {
       @Component({