Cannot read properties of undefined (reading 'title') is thrown when …

…adding and removing a toolbox item dynamically fix #5271 (#5272)

packages/survey-creator-core/src/creator-base.ts

@@ -3191,14 +3191,13 @@ export class SurveyCreatorModel extends Base
       currentAddQuestionType = this.currentAddQuestionType;
     if (!!currentAddQuestionType) {
       const str = this.getLocString("ed.addNewTypeQuestion");
-      if (!!str && !!str["format"])
-        return str["format"](
-          this.toolbox.items.filter((item) => item.name == currentAddQuestionType)[0].title
-        );
+      const items = this.toolbox.items.filter((item) => item.name == currentAddQuestionType);
+      if (Array.isArray(items) && items.length > 0 && !!str && !!str["format"]) {
+        return str["format"](items[0].title);
+      }
     }
     return this.getLocString("ed.addNewQuestion");
   }
-
   public get addNewQuestionText() {
     return this.getAddNewQuestionText();
   }

packages/survey-creator-core/tests/creator-base.tests.ts

@@ -4377,4 +4377,17 @@ test("New ghost page shouldn't be created if onPageAdding sets allow to false",
   expect(creator.survey.pages).toHaveLength(1);
   expect(desigerTab.newPage).toBeFalsy();
   expect(desigerTab.showNewPage).toBeFalsy();
+});
+test("Add-remove toolbox items, #5271", (): any => {
+  const creator = new CreatorTester();
+  creator.toolbox.allowExpandMultipleCategories = true;
+  creator.toolbox.showCategoryTitles = true;
+  creator.onQuestionAdded.add((sender, options) => {
+    if (options.question.getType() === "dropdown") {
+      creator.toolbox.removeItem("dropdown");
+    }
+  });
+  creator.currentAddQuestionType = "dropdown";
+  creator.addNewQuestionInPage(() => {}, undefined, "dropdown");
+  expect(creator.getAddNewQuestionText()).toEqual("Add Question");
 });