diff --git a/src/database.ts b/src/database.ts
index c8b3d48..6a7c543 100644
--- a/src/database.ts
+++ b/src/database.ts
@@ -4,6 +4,11 @@ import sqlite3 from "sqlite3";
 const dbDirectory = "./src/db";
 const dbFilePath = `${dbDirectory}/database.db`;
 
+export type error = {
+  errno: number;
+  code: string;
+};
+
 /* Fonction pour exécuter une requête sur la base de données */
 
 /* Fonction pour exécuter une requête de modification de la base de données (INSERT, UPDATE, DELETE) */
@@ -111,15 +116,25 @@ export function createRegisteredUserTable(db: sqlite3.Database): Promise<void> {
 }
 
 /* Insérer un utilisateur dans la table registered_user */
-export function insertUser(
+export async function insertUser(
   db: sqlite3.Database,
   login: string,
   password: string,
   permissions: number
-) {
+): Promise<boolean> {
   const insertUserQuery = `INSERT INTO registered_user (login, password, permissions) VALUES (?, ?, ?)`;
 
-  return runDB(db, insertUserQuery, [login, password, permissions]);
+  try {
+    await runDB(db, insertUserQuery, [login, password, permissions]);
+    return true;
+  } catch (e) {
+    const error = e as error;
+    if (error.code === "SQLITE_CONSTRAINT") {
+      return false;
+    } else {
+      throw e;
+    }
+  }
 }
 
 /* Modifier le login d'un utilisateur dans la table registered_user */
diff --git a/src/server.ts b/src/server.ts
index 8690712..702d825 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -1,5 +1,5 @@
 import cors from "@fastify/cors";
-import websocket, { WebSocket } from '@fastify/websocket';
+import websocket, { WebSocket } from "@fastify/websocket";
 import { Type, TypeBoxTypeProvider } from "@fastify/type-provider-typebox";
 import Fastify, { FastifyReply } from "fastify";
 import { nanoid } from "nanoid";
@@ -18,13 +18,13 @@ const clients: Record<string, FastifyReply> = {};
 const generateId = () => nanoid(32);
 
 let updates: Update[] = [];
-let doc = Text.of(['']);
+let doc = Text.of([""]);
 const liveClients: WebSocket[] = [];
 
 function send(socket: WebSocket, requestId: number, payload: unknown) {
   const response = {
     _request: requestId,
-    payload
+    payload,
   };
   socket.send(JSON.stringify(response));
 }
@@ -33,70 +33,78 @@ const fastify = Fastify({
   logger: true,
 }).withTypeProvider<TypeBoxTypeProvider>();
 await fastify.register(cors, {
-  origin: process.env.ALLOW_ORIGIN || '*',
+  origin: process.env.ALLOW_ORIGIN || "*",
 });
 fastify.register(websocket);
 fastify.get("/live", { websocket: true }, (socket, req) => {
   liveClients.push(socket);
-  socket.on("message", message => {
+  socket.on("message", (message) => {
     const data = JSON.parse(message.toString());
     const requestId = data._request;
     if (data.type === "pullUpdates") {
-      send(socket, requestId, updates.slice(data.version))
+      send(socket, requestId, updates.slice(data.version));
     } else if (data.type === "pushUpdates") {
       let received = data.updates.map((json: any) => ({
         clientID: json.clientID,
-        changes: ChangeSet.fromJSON(json.changes)
-      }))
+        changes: ChangeSet.fromJSON(json.changes),
+      }));
       if (data.version != updates.length) {
-        received = rebaseUpdates(received, updates.slice(data.version))
+        received = rebaseUpdates(received, updates.slice(data.version));
       }
       for (let update of received) {
-        updates.push(update)
-        doc = update.changes.apply(doc)
+        updates.push(update);
+        doc = update.changes.apply(doc);
       }
-      send(socket, requestId, received.map((update: any) => ({
-        clientID: update.clientID,
-        changes: update.changes.toJSON()
-      })));
+      send(
+        socket,
+        requestId,
+        received.map((update: any) => ({
+          clientID: update.clientID,
+          changes: update.changes.toJSON(),
+        }))
+      );
     } else if (data.type == "getDocument") {
-      send(socket, requestId, {version: updates.length, doc: doc.toString()})
+      send(socket, requestId, { version: updates.length, doc: doc.toString() });
     }
-  })
-})
-
-fastify.post("/run", {
-  schema: {
-    body: Type.Object({
-      code: Type.String(),
-      language: Type.String(),
-    }),
-  },
-}, (req, reply) => {
-  const { code, language } = req.body;
-  const runner = getRunner(language);
-  if (runner === null) {
-    return reply.status(422).send({ error: "Invalid language" });
-  }
-  const jobId = generateId();
-  const buffer = allocateBuffer(jobId, code, runner);
-  reply.raw.writeHead(200, {
-    "Content-Type": "text/event-stream",
-    Connection: "keep-alive",
-    "Cache-Control": "no-cache",
-    "Access-Control-Allow-Origin": process.env.ALLOW_ORIGIN || "*",
-  });
-  reply.raw.on("close", () => {
-    delete clients[jobId];
   });
-  sender.send(buffer).then(() => {
-    reply.raw.write("event: connected\n");
-    reply.raw.write(`data: ${jobId}\n`);
-    reply.raw.write("id: 0\n\n");
-  });
-  clients[jobId] = reply;
 });
 
+fastify.post(
+  "/run",
+  {
+    schema: {
+      body: Type.Object({
+        code: Type.String(),
+        language: Type.String(),
+      }),
+    },
+  },
+  (req, reply) => {
+    const { code, language } = req.body;
+    const runner = getRunner(language);
+    if (runner === null) {
+      return reply.status(422).send({ error: "Invalid language" });
+    }
+    const jobId = generateId();
+    const buffer = allocateBuffer(jobId, code, runner);
+    reply.raw.writeHead(200, {
+      "Content-Type": "text/event-stream",
+      Connection: "keep-alive",
+      "Cache-Control": "no-cache",
+      "Access-Control-Allow-Origin": process.env.ALLOW_ORIGIN || "*",
+    });
+    reply.raw.on("close", () => {
+      delete clients[jobId];
+    });
+    sender.send(buffer).then(() => {
+      reply.raw.write("event: connected\n");
+      reply.raw.write(`data: ${jobId}\n`);
+      reply.raw.write("id: 0\n\n");
+    });
+    clients[jobId] = reply;
+  }
+);
+
 /* Création du répertoire de la base de données s'il n'existe pas */
 db.createDbDirectory();
 
@@ -120,8 +128,11 @@ fastify.post(
   },
   async (request, reply) => {
     const { login, password, permissions } = request.body;
-    db.insertUser(database, login, password, permissions);
-    reply.send({ success: true });
+    if (!(await db.insertUser(database, login, password, permissions))) {
+      reply.send({ success: false });
+    } else {
+      reply.send({ success: true });
+    }
   }
 );