Fixed a issue while deleting categories - Polishing UI

main.ts

@@ -1,4 +1,4 @@
-import { Plugin } from "obsidian";
+import { Plugin, Notice } from "obsidian";
 import { TaskWeaverView, VIEW_TYPE_TASKWEAVER } from "./view";
 import { TaskWeaverSettingTab } from "./settings";
 import { TaskWeaverSettings, DEFAULT_SETTINGS, Task, Category } from "./types";
@@ -91,6 +91,7 @@ export default class TaskWeaverPlugin extends Plugin {
 	async deleteCategory(categoryId: string): Promise<void> {
 		const hasTasks = this.settings.tasks.some(t => t.categoryId === categoryId);
 		if (hasTasks) {
+			new Notice("Cannot delete category: it still contains tasks. Please delete or move all tasks first.");
 			return;
 		}