Add migration

static/data_migration.mts

@@ -0,0 +1,37 @@
+import { LocalStorage } from "./storage_manager.mjs"
+
+type InstanceV0 = {
+    name: string,
+    origin: string,
+    software: string,
+    iconURL?: string,
+    preferredFor?: string[],
+}
+type LocalStorageV0 = {
+    version: undefined,
+    instances: InstanceV0[],
+}
+
+type LocalStorageV1 = LocalStorage;
+
+function migrate0to1(s: LocalStorageV0): LocalStorageV1 {
+    return {
+        version: 1,
+        instances: s.instances.map(i => ({
+            preferredFor: i.preferredFor ?? [],
+            ...i
+        }))
+    };
+}
+
+type AnyLocalStorage = LocalStorageV0 | LocalStorageV1;
+
+export default function migrate(storage: AnyLocalStorage): LocalStorage {
+    switch (storage.version) {
+        case undefined:
+            storage = migrate0to1(storage);
+        case 1:
+        default:
+            return storage;
+    }
+}

static/storage_manager.mts

@@ -1,3 +1,5 @@
+import migrate from "./data_migration.mjs";
+
 export type Instance = {
     /**
      * The instance's (nick)name
@@ -21,18 +23,19 @@ export type Instance = {
     software: string,
     /**
      * The instance's icon URL
-     * 
-     * Make sure to sanitize this! Could lead to XSS
+     * @example undefined
+     * @example "https://void.lgbt/favicon.png"
      */
     iconURL?: string,
     /**
      * The list of software names and groups the user prefers to autoredirect to this instance
      * @example ["sharkey", "misskey-compliant"]
      */
-    preferredFor?: string[],
+    preferredFor: string[],
 }
 
-type LocalStorage = {
+export type LocalStorage = {
+    version: number,
     instances: Instance[],
 }
 
@@ -46,12 +49,14 @@ export default new class StorageManager {
 
     default(): LocalStorage {
         return {
+            version: 1,
             instances: []
         }
     }
 
     load() {
-        this.storage = JSON.parse(window.localStorage.getItem("storage") ?? "null") ?? this.default();
+        const data = JSON.parse(window.localStorage.getItem("storage") ?? "null") ?? this.default();
+        this.storage = migrate(data);
     }
 
     save() {