fix(material/datepicker): error if some methods are called too early. (#32630)

Fixes that the `focusActiveCell` and `updateTodaysDate` methods on `MatCalendar` were throwing an error if they're called too early.

Fixes #32627.

Author: crisbeto

src/material/datepicker/calendar.spec.ts

@@ -639,6 +639,28 @@ describe('MatCalendar', () => {
       });
     });
   });
+
+  it("should not throw when updating today's date too early", () => {
+    const fixture = TestBed.createComponent(StandardCalendar);
+    const calendar = fixture.debugElement.query(By.directive(MatCalendar))
+      .componentInstance as MatCalendar<Date>;
+
+    expect(() => {
+      calendar.updateTodaysDate();
+      fixture.detectChanges();
+    }).not.toThrow();
+  });
+
+  it('should not throw when focusing the active cell too early', () => {
+    const fixture = TestBed.createComponent(StandardCalendar);
+    const calendar = fixture.debugElement.query(By.directive(MatCalendar))
+      .componentInstance as MatCalendar<Date>;
+
+    expect(() => {
+      calendar.focusActiveCell();
+      fixture.detectChanges();
+    }).not.toThrow();
+  });
 });
 
 @Component({

src/material/datepicker/calendar.ts

@@ -499,12 +499,12 @@ export class MatCalendar<D> implements AfterContentInit, AfterViewChecked, OnDes
 
   /** Focuses the active date. */
   focusActiveCell() {
-    this._getCurrentViewComponent()._focusActiveCell(false);
+    this._getCurrentViewComponent()?._focusActiveCell(false);
   }
 
   /** Updates today's date after an update of the active date */
   updateTodaysDate() {
-    this._getCurrentViewComponent()._init();
+    this._getCurrentViewComponent()?._init();
   }
 
   /** Handles date selection in the month view. */
@@ -557,7 +557,11 @@ export class MatCalendar<D> implements AfterContentInit, AfterViewChecked, OnDes
   }
 
   /** Returns the component instance that corresponds to the current calendar view. */
-  private _getCurrentViewComponent(): MatMonthView<D> | MatYearView<D> | MatMultiYearView<D> {
+  private _getCurrentViewComponent():
+    | MatMonthView<D>
+    | MatYearView<D>
+    | MatMultiYearView<D>
+    | undefined {
     // The return type is explicitly written as a union to ensure that the Closure compiler does
     // not optimize calls to _init(). Without the explicit return type, TypeScript narrows it to
     // only the first component type. See https://github.com/angular/components/issues/22996.