Add URL validation check to prevent crash (facebook#55748)

Summary:

Add defensive check to validate the WebSocket URL before attempting to connect.
This prevents potential crashes when an invalid or nil URL is passed to the WebSocket module, which could cause XPC serialization failures deep in the network stack.

The crash was observed in during XPC serialization when SocketRocket attempted to open a connection with invalid URL data.

Changelog: [Internal]

Differential Revision: D94375527

Author: vzaidman

packages/react-native/React/CoreModules/RCTWebSocketModule.mm

@@ -10,6 +10,7 @@
 #import <objc/runtime.h>
 
 #import <FBReactNativeSpec/FBReactNativeSpec.h>
+#import <React/RCTAssert.h>
 #import <React/RCTConvert.h>
 #import <React/RCTUtils.h>
 #import <SocketRocket/SRWebSocket.h>
@@ -66,6 +67,14 @@ - (void)invalidate
     connect : (NSURL *)URL protocols : (NSArray *)protocols options : (JS::NativeWebSocketModule::SpecConnectOptions &)
         options socketID : (double)socketID)
 {
+  if ((URL == nullptr) || URL.absoluteString.length == 0u) {
+    RCTAssert(NO, @"RCTWebSocketModule: Invalid WebSocket URL passed to connect");
+    NSNumber *socketIDNumber = @(socketID);
+    NSDictionary *body = @{@"message" : @"Invalid WebSocket URL", @"id" : socketIDNumber};
+    [self sendEventWithName:@"websocketFailed" body:body];
+    return;
+  }
+
   NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
 
   // We load cookies from sharedHTTPCookieStorage (shared with XHR and