Prevent "already disposed" errors when trying to kill disposed proxies

Author: code-asher

packages/protocol/src/browser/client.ts

@@ -15,6 +15,7 @@ interface ProxyData {
 	promise: Promise<void>;
 	instance: any;
 	callbacks: Map<number, (...args: any[]) => void>;
+	disposed: boolean;
 }
 
 /**
@@ -174,9 +175,10 @@ export class Client {
 	 * Make a remote call for a proxy's method using proto.
 	 */
 	private remoteCall(proxyId: number | Module, method: string, args: any[]): Promise<any> {
-		if (this.disconnected && typeof proxyId === "number") {
-			// Can assume killing or closing works because a disconnected proxy
-			// is disposed on the server's side.
+		if (typeof proxyId === "number" && (this.disconnected || !this.proxies.has(proxyId))) {
+			// Can assume killing or closing works because a disconnected proxy is
+			// disposed on the server's side, and a non-existent proxy has already
+			// been disposed.
 			switch (method) {
 				case "close":
 				case "kill":
@@ -469,6 +471,7 @@ export class Client {
 			promise,
 			instance,
 			callbacks: new Map(),
+			disposed: false,
 		});
 
 		instance.onDone(() => {