Null Exception Handling | Input Validation - RCTAlertController - RCTDevLoadingView (#35689)

Summary:
Enhancing native iOS modules and preventing crashes inside the RCTAlertController

## Changelog
[iOS][Fixed] - Handle properly a `nil` `keyWindows` in the AlertController

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Pull Request resolved: #35689

Reviewed By: cipolleschi

Differential Revision: D42179169

Pulled By: ryancat

fbshipit-source-id: 05a6788f610db1d222e3c10b3c774c75edaf55f5

Author: admirsaheta

React/CoreModules/RCTAlertController.m

@@ -20,10 +20,17 @@ @implementation RCTAlertController
 - (UIWindow *)alertWindow
 {
   if (_alertWindow == nil) {
-    _alertWindow = [[UIWindow alloc] initWithFrame:RCTSharedApplication().keyWindow.bounds];
-    _alertWindow.rootViewController = [UIViewController new];
-    _alertWindow.windowLevel = UIWindowLevelAlert + 1;
+    UIWindow *keyWindow = RCTSharedApplication().keyWindow;
+    if (keyWindow) {
+      _alertWindow = [[UIWindow alloc] initWithFrame:keyWindow.bounds];
+      _alertWindow.rootViewController = [UIViewController new];
+      _alertWindow.windowLevel = UIWindowLevelAlert + 1;
+    } else {
+      // keyWindow is nil, so we cannot create and initialize _alertWindow
+      NSLog(@"Unable to create alert window: keyWindow is nil");
+    }
   }
+
   return _alertWindow;
 }
 

React/CoreModules/RCTDevLoadingView.mm

@@ -110,6 +110,20 @@ - (void)showMessage:(NSString *)message color:(UIColor *)color backgroundColor:(
     return;
   }
 
+  // Input validation
+  if (message == nil || [message isEqualToString:@""]) {
+    NSLog(@"Error: message cannot be nil or empty");
+    return;
+  }
+  if (color == nil) {
+    NSLog(@"Error: color cannot be nil");
+    return;
+  }
+  if (backgroundColor == nil) {
+    NSLog(@"Error: backgroundColor cannot be nil");
+    return;
+  }
+
   dispatch_async(dispatch_get_main_queue(), ^{
     self->_showDate = [NSDate date];
     if (!self->_window && !RCTRunningInTestEnvironment()) {