Construct plugins with a static fromContext (#487)

Each plugin class now has a private constructor and a static async
fromContext(context) that loads its datastores, constructs the instance
and attaches its handlers and hooks. This replaces the public constructor
followed by init(), and AutoRestart's start().

Datastores are loaded before construction and passed to the constructor,
so the definite assignment assertions on them are gone. Tests build the
plugins through fromContext and pass a wrapped logger in the context
instead of overwriting plugin.logger before init().

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

exp_server_ups/instance.ts

@@ -2,24 +2,25 @@ import * as lib from "@clusterio/lib";
 import type { Instance, InstancePluginContext } from "@clusterio/host";
 
 export class InstancePlugin {
-	instance: Instance;
-	logger: lib.Logger;
-	name: string;
 	private updateInterval?: ReturnType<typeof setInterval>;
 	private gameTimes: number[] = [];
 
-	constructor(context: InstancePluginContext) {
-		this.instance = context.instance;
-		this.logger = context.logger;
-		this.name = context.plugin.name;
-	}
+	private constructor(
+		public instance: Instance,
+		public logger: lib.Logger,
+		public name: string,
+	) {}
 
-	init() {
-		const hooks = this.instance.hooks;
-		hooks.start.attach(this.name, this.onStart.bind(this));
-		hooks.exit.attach(this.name, this.onExit.bind(this));
-		hooks.instanceConfigFieldChanged.attach(this.name, this.onInstanceConfigFieldChanged.bind(this));
-		hooks.playerEvent.attach(this.name, this.onPlayerEvent.bind(this));
+	static async fromContext(context: InstancePluginContext) {
+		const instance = context.instance;
+		const plugin = new InstancePlugin(instance, context.logger, context.plugin.name);
+
+		const hooks = instance.hooks;
+		hooks.start.attach(plugin.name, plugin.onStart.bind(plugin));
+		hooks.exit.attach(plugin.name, plugin.onExit.bind(plugin));
+		hooks.instanceConfigFieldChanged.attach(plugin.name, plugin.onInstanceConfigFieldChanged.bind(plugin));
+		hooks.playerEvent.attach(plugin.name, plugin.onPlayerEvent.bind(plugin));
+		return plugin;
 	}
 
 	async onStart() {
@@ -86,5 +87,5 @@ export class InstancePlugin {
 }
 
 export default async function (context: InstancePluginContext) {
-	new InstancePlugin(context).init();
+	await InstancePlugin.fromContext(context);
 }