refactor: export TransportError (#709)

Author: jbaldassari

lib/index.ts

@@ -3,7 +3,7 @@ import { Socket } from "./socket.js";
 export { Socket };
 export { SocketOptions } from "./socket.js";
 export const protocol = Socket.protocol;
-export { Transport } from "./transport.js";
+export { Transport, TransportError } from "./transport.js";
 export { transports } from "./transports/index.js";
 export { installTimerFunctions } from "./util.js";
 export { parse } from "./contrib/parseuri.js";

lib/transport.ts

@@ -8,7 +8,7 @@ import { encode } from "./contrib/parseqs.js";
 
 const debug = debugModule("engine.io-client:transport"); // debug()
 
-class TransportError extends Error {
+export class TransportError extends Error {
   public readonly type = "TransportError";
 
   constructor(