fix(typings): do not expose browser-specific types

Related:

- socketio/socket.io-client#1561
- b9252e2

Author: darrachequesne

lib/transport.ts

@@ -21,7 +21,7 @@ class TransportError extends Error {
 
 export interface CloseDetails {
   description: string;
-  context?: CloseEvent | XMLHttpRequest;
+  context?: unknown; // context should be typed as CloseEvent | XMLHttpRequest, but these types are not available on non-browser platforms
 }
 
 interface TransportReservedEvents {

lib/transports/polling.ts

@@ -292,7 +292,7 @@ export class Polling extends Transport {
 interface RequestReservedEvents {
   success: () => void;
   data: (data: RawData) => void;
-  error: (err: number | Error, context: XMLHttpRequest) => void;
+  error: (err: number | Error, context: unknown) => void; // context should be typed as XMLHttpRequest, but this type is not available on non-browser platforms
 }
 
 export class Request extends Emitter<{}, {}, RequestReservedEvents> {