Fix TypeError in IgxTextHighlightDirective when destroyed before ngAfterViewInit (#16615)

* Add null check to clearHighlight() and test for early destruction

Author: Copilot

projects/igniteui-angular/directives/src/directives/text-highlight/text-highlight.directive.spec.ts

@@ -308,6 +308,15 @@ describe('IgxHighlight', () => {
 
         expect(() => component.highlight.activateIfNecessary()).not.toThrowError();
     });
+
+    it('Should not throw error when destroyed before ngAfterViewInit completes', () => {
+        // Create the component but do NOT call detectChanges()
+        // This simulates the directive being destroyed before ngAfterViewInit is called
+        const fix = TestBed.createComponent(HighlightLoremIpsumComponent);
+
+        // Destroy the component without initializing it
+        expect(() => fix.destroy()).not.toThrowError();
+    });
 });
 
 @Component({

projects/igniteui-angular/directives/src/directives/text-highlight/text-highlight.directive.ts

@@ -302,8 +302,10 @@ export class IgxTextHighlightDirective implements AfterViewInit, AfterViewChecke
     public clearHighlight(): void {
         this.clearChildElements(false);
 
-        this._lastSearchInfo.searchText = '';
-        this._lastSearchInfo.matchCount = 0;
+        if (this._lastSearchInfo) {
+            this._lastSearchInfo.searchText = '';
+            this._lastSearchInfo.matchCount = 0;
+        }
     }
 
     /**