Replace use of null with undefined to stop sending chat actions

src/README.md

@@ -112,8 +112,8 @@ actions for the current update.
 // Set the action to be sent until the update is processed
 ctx.chatAction = "typing";
 
-// To stop sending the chat action, simply set it to null
-ctx.chatAction = null;
+// To stop sending the chat action, simply set it to undefined
+ctx.chatAction = undefined;
 
 // You can change the chat action during update processing
 ctx.chatAction = "choose_sticker";
@@ -135,7 +135,7 @@ await ctx.replyWithPhoto(
 );
 
 // There is no ongoing chat action now
-// ctx.chatAction is null
+// ctx.chatAction is undefined
 ```
 
 #### Sending Chat Action with Middleware

src/auto-chat-action.ts

@@ -4,7 +4,7 @@ import { createChatActionsController } from "./chat-actions-controller.ts";
 import { getChatActionsForRequest } from "./extract-chat-actions.ts";
 
 export type AutoChatActionFlavor = {
-  chatAction: Action | null;
+  chatAction: Action | undefined;
 };
 
 export function autoChatAction<C extends Context>(
@@ -56,12 +56,12 @@ export function autoChatAction<C extends Context>(
             payload.chat_id,
             messageThreadId,
           );
-          currentAction = null;
+          currentAction = undefined;
         }
       },
     );
 
-    let currentAction: Action | null = null;
+    let currentAction: Action | undefined = undefined;
     Object.defineProperty(ctx, "chatAction", {
       get() {
         return currentAction;

test/auto-chat-action.test.ts

@@ -1267,7 +1267,7 @@ describe("autoChatAction middleware", () => {
 
         await ctx.api.sendPhoto(chat_id, photo, {}, signal);
 
-        assertEquals(ctx.chatAction, null);
+        assertEquals(ctx.chatAction, undefined);
       });
 
       await bot.handleUpdate({
@@ -1386,7 +1386,7 @@ describe("autoChatAction middleware", () => {
         ctx.chatAction = "typing";
         ctx.chatAction = "choose_sticker";
         await time.tickAsync(actionSendingInterval);
-        ctx.chatAction = null;
+        ctx.chatAction = undefined;
         await time.tickAsync(actionSendingInterval * 2);
         ctx.chatAction = "find_location";