chore: add error handling topic in docs

docs/.vitepress/config.mts

@@ -81,6 +81,7 @@ export default defineConfig({
 					},
 					{ text: "Formatting", link: "/formatting/index" },
 					{ text: "Types", link: "/types/index" },
+					{ text: "Error Handling", link: "/error-handling/index" },
 				],
 			},
 		],

docs/error-handling/index.md

@@ -0,0 +1,56 @@
+# Error Handling
+
+It happens that errors occur in middleware and we need to handle them.
+That's what the `onError` method was created for.
+
+```ts twoslash
+import { Bot } from "gramio";
+
+const bot = new Bot("");
+// ---cut---
+
+bot.updates.on("message", () => {
+    bot.api.sendMessage({
+        chat_id: "@not_found",
+        text: "Chat not exists....",
+    });
+});
+
+bot.updates.onError(({ context, kind, error }) => {
+    if (context.is("message")) return context.send(`${kind}: ${error.message}`);
+});
+```
+
+## Errors
+
+### Telegram
+
+This error is the result of a failed request to the Telegram Bot API
+
+```ts twoslash
+import { Bot } from "gramio";
+
+const bot = new Bot("");
+// ---cut---
+bot.updates.onError(({ context, kind, error }) => {
+    if (kind === "TELEGRAM" && error.method === "sendMessage") {
+        error.params; // is sendMessage params
+    }
+});
+```
+
+### Unknown
+
+This error is any unknown error, whether it's your class or just an Error.
+
+```ts twoslash
+import { Bot } from "gramio";
+
+const bot = new Bot("");
+// ---cut---
+bot.updates.onError(({ context, kind, error }) => {
+    if (kind === "UNKNOWN") {
+        console.log(error.message);
+    }
+});
+```