Retry loading map on variable error

If the back is getting an error (because the user has no right to set a variable),
instead of failing directly, let's try to reload the map (maybe we have cached a wrong version of the map).

back/src/Model/GameRoom.ts

@@ -26,6 +26,7 @@ import { VariablesManager } from "../Services/VariablesManager";
 import { ADMIN_API_URL } from "../Enum/EnvironmentVariable";
 import { LocalUrlError } from "../Services/LocalUrlError";
 import { emitErrorOnRoomSocket } from "../Services/MessageHelpers";
+import { VariableError } from "../Services/VariableError";
 
 export type ConnectCallback = (user: User, group: Group) => void;
 export type DisconnectCallback = (user: User, group: Group) => void;
@@ -336,6 +337,7 @@ export class GameRoom {
         // First, let's check if "user" is allowed to modify the variable.
         const variableManager = await this.getVariableManager();
 
+        try {
             const readableBy = variableManager.setVariable(name, value, user);
 
             // If the variable was not changed, let's not dispatch anything.
@@ -361,6 +363,36 @@ export class GameRoom {
             for (const socket of this.roomListeners) {
                 socket.write(batchMessage);
             }
+        } catch (e) {
+            if (e instanceof VariableError) {
+                // Ok, we have an error setting a variable. Either the user is trying to hack the map... or the map
+                // is not up to date. So let's try to reload the map from scratch.
+                if (this.variableManagerLastLoad === undefined) {
+                    throw e;
+                }
+                const lastLoaded = new Date().getTime() - this.variableManagerLastLoad.getTime();
+                if (lastLoaded < 10000) {
+                    console.log(
+                        'An error occurred while setting the "' +
+                            name +
+                            "\" variable. But we tried to reload the map less than 10 seconds ago, so let's fail."
+                    );
+                    // Do not try to reload if we tried to reload less than 10 seconds ago.
+                    throw e;
+                }
+
+                // Reset the variable manager
+                this.variableManagerPromise = undefined;
+
+                console.log(
+                    'An error occurred while setting the "' + name + "\" variable. Let's reload the map and try again"
+                );
+                // Try to set the variable again!
+                await this.setVariable(name, value, user);
+            } else {
+                throw e;
+            }
+        }
     }
 
     public addZoneListener(call: ZoneSocket, x: number, y: number): Set<Movable> {
@@ -449,11 +481,13 @@ export class GameRoom {
     }
 
     private variableManagerPromise: Promise<VariablesManager> | undefined;
+    private variableManagerLastLoad: Date | undefined;
 
     private getVariableManager(): Promise<VariablesManager> {
         if (!this.variableManagerPromise) {
             this.variableManagerPromise = this.getMap()
                 .then((map) => {
+                    this.variableManagerLastLoad = new Date();
                     const variablesManager = new VariablesManager(this.roomUrl, map);
                     return variablesManager.init();
                 })

back/src/Services/VariableError.ts

@@ -0,0 +1,9 @@
+/**
+ * Errors related to variable handling.
+ */
+export class VariableError extends Error {
+    constructor(message: string) {
+        super(message);
+        Object.setPrototypeOf(this, VariableError.prototype);
+    }
+}

back/src/Services/VariablesManager.ts

@@ -10,6 +10,7 @@ import {
 import { User } from "_Model/User";
 import { variablesRepository } from "./Repository/VariablesRepository";
 import { redisClient } from "./RedisClient";
+import { VariableError } from "./VariableError";
 
 interface Variable {
     defaultValue?: string;
@@ -174,11 +175,13 @@ export class VariablesManager {
         if (this.variableObjects) {
             variableObject = this.variableObjects.get(name);
             if (variableObject === undefined) {
-                throw new Error('Trying to set a variable "' + name + '" that is not defined as an object in the map.');
+                throw new VariableError(
+                    'Trying to set a variable "' + name + '" that is not defined as an object in the map.'
+                );
             }
 
             if (variableObject.writableBy && !user.tags.includes(variableObject.writableBy)) {
-                throw new Error(
+                throw new VariableError(
                     'Trying to set a variable "' +
                         name +
                         '". User "' +