fix(chips): Do not throw error if chip set becomes empty (#5290)

Author: bonniezhou

packages/mdc-chips/chip-set/foundation.ts

@@ -110,6 +110,12 @@ export class MDCChipSetFoundation extends MDCFoundation<MDCChipSetAdapter> {
     this.adapter_.removeChipAtIndex(index);
     const maxIndex = this.adapter_.getChipListCount() - 1;
     const nextIndex = Math.min(index, maxIndex);
+
+    // Early exit if there are no other chips in the set
+    if (nextIndex < 0) {
+      return;
+    }
+
     this.removeFocusFromChipsExcept_(nextIndex);
     // After removing a chip, we should focus the trailing action for the next chip.
     this.adapter_.focusChipTrailingActionAtIndex(nextIndex);

test/unit/mdc-chips/mdc-chip-set.foundation.test.js

@@ -245,6 +245,15 @@ test('#handleChipRemoval gives focus to the next chip', () => {
   td.verify(mockAdapter.focusChipTrailingActionAtIndex(1));
 });
 
+test('#handleChipRemoval does not throw error if chip set is left empty', () => {
+  const {foundation, mockAdapter} = setupTest();
+  td.when(mockAdapter.getChipListCount()).thenReturn(0);
+  td.when(mockAdapter.getIndexOfChipById('chipA')).thenReturn(0);
+
+  foundation.handleChipRemoval('chipA');
+  td.verify(mockAdapter.focusChipTrailingActionAtIndex(-1), {times: 0});
+});
+
 function setupChipNavigationTest(chipIds, isRTL=false) {
   const {foundation, mockAdapter} = setupTest();
   td.when(mockAdapter.getIndexOfChipById(td.matchers.isA(String))).thenDo((id) => {