Improve error handling of API (#4345)

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* Update attached_notes.ts

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* Refactor

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* Update call.ts

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* ✌️

* Fix

src/server/api/endpoints/i/unpin.ts

@@ -3,6 +3,7 @@ import ID, { transform } from '../../../../misc/cafy-id';
 import { pack } from '../../../../models/user';
 import { removePinned } from '../../../../services/i/pin';
 import define from '../../define';
+import { ApiError } from '../../error';
 
 export const meta = {
 	stability: 'stable',
@@ -24,22 +25,24 @@ export const meta = {
 				'en-US': 'Target note ID'
 			}
 		}
+	},
+
+	errors: {
+		noSuchNote: {
+			message: 'No such note.',
+			code: 'NO_SUCH_NOTE',
+			id: '454170ce-9d63-4a43-9da1-ea10afe81e21'
+		},
 	}
 };
 
-export default define(meta, (ps, user) => new Promise(async (res, rej) => {
-	// Processing
-	try {
-		await removePinned(user, ps.noteId);
-	} catch (e) {
-		return rej(e.message);
-	}
-
-	// Serialize
-	const iObj = await pack(user, user, {
-		detail: true
+export default define(meta, async (ps, user) => {
+	await removePinned(user, ps.noteId).catch(e => {
+		if (e.id === 'b302d4cf-c050-400a-bbb3-be208681f40c') throw new ApiError(meta.errors.noSuchNote);
+		throw e;
 	});
 
-	// Send response
-	res(iObj);
-}));
+	return await pack(user, user, {
+		detail: true
+	});
+});