add error logs for nil moduleRegistry

Summary:
Changelog: [Internal]

for the last 6 months or so, we've been getting this task where the moduleRegistry in RCTDeviceInfo is nil. in this change, i add some logs to see what might be setting this to nil.

 in all honestly, i don't really think this is happening, but it would be good to verify.

Reviewed By: sshic

Differential Revision: D34908902

fbshipit-source-id: d375285467a87453605ba0fecfc124bc3bff6e63

React/CoreModules/RCTDeviceInfo.mm

@@ -69,6 +69,14 @@ RCT_EXPORT_MODULE()
                                              object:nil];
 }
 
+- (void)setModuleRegistry:(RCTModuleRegistry *)moduleRegistry
+{
+  if (!moduleRegistry) {
+    RCTAssert(false, @"moduleRegistry should not be nil, _moduleRegistry is nil: %d", _moduleRegistry == nil);
+  }
+  _moduleRegistry = moduleRegistry;
+}
+
 static BOOL RCTIsIPhoneX()
 {
   static BOOL isIPhoneX = NO;