Properly handle null values coming from JS (facebook#49250)

Summary:
Pull Request resolved: facebook#49250

The TurboModule System decided to ignore the Null values when they are coming to JS. However, in iOS, null value can be mapped to `[NSNull null];` and this value is a valid value that can be used on the native side.

In the old architecture, when the user were sending a null value from JS to a native module, the Native side was receiving the value.

In the New Architecture, the value was stripped away.

This change allow us to handle the `null` value properly in the interop layer, to restore the usage of legacy modules in the New Arch.

I also tried with a more radical approach, but several tests were crashing because some modules do not know how to handle `NSNull`.

See discussion happening here: invertase/react-native-firebase#8144 (comment)

## Changelog:
[iOS][Changed] - Properly handle `null` values coming from NativeModules.

Reviewed By: sammy-SC

Differential Revision: D69301396

fbshipit-source-id: be275185e2643092f6c3dc2481fe9381bbcf69e9

packages/react-native/ReactCommon/react/nativemodule/core/platform/ios/ReactCommon/RCTInteropTurboModule.mm

@@ -346,7 +346,7 @@ T RCTConvertTo(SEL selector, id json)
   SEL selector = selectorForType(argumentType);
 
   if ([RCTConvert respondsToSelector:selector]) {
-    id objCArg = TurboModuleConvertUtils::convertJSIValueToObjCObject(runtime, jsiArg, jsInvoker_);
+    id objCArg = TurboModuleConvertUtils::convertJSIValueToObjCObject(runtime, jsiArg, jsInvoker_, YES);
 
     if (objCArgType == @encode(char)) {
       char arg = RCTConvertTo<char>(selector, objCArg);
@@ -500,7 +500,7 @@ T RCTConvertTo(SEL selector, id json)
     }
 
     RCTResponseSenderBlock arg =
-        (RCTResponseSenderBlock)TurboModuleConvertUtils::convertJSIValueToObjCObject(runtime, jsiArg, jsInvoker_);
+        (RCTResponseSenderBlock)TurboModuleConvertUtils::convertJSIValueToObjCObject(runtime, jsiArg, jsInvoker_, YES);
     if (arg) {
       [retainedObjectsForInvocation addObject:arg];
     }
@@ -515,7 +515,7 @@ T RCTConvertTo(SEL selector, id json)
     }
 
     RCTResponseSenderBlock senderBlock =
-        (RCTResponseSenderBlock)TurboModuleConvertUtils::convertJSIValueToObjCObject(runtime, jsiArg, jsInvoker_);
+        (RCTResponseSenderBlock)TurboModuleConvertUtils::convertJSIValueToObjCObject(runtime, jsiArg, jsInvoker_, YES);
     RCTResponseErrorBlock arg = ^(NSError *error) {
       senderBlock(@[ RCTJSErrorFromNSError(error) ]);
     };
@@ -545,7 +545,7 @@ T RCTConvertTo(SEL selector, id json)
           runtime, errorPrefix + "JavaScript argument must be a plain object. Got " + getType(runtime, jsiArg));
     }
 
-    id arg = TurboModuleConvertUtils::convertJSIValueToObjCObject(runtime, jsiArg, jsInvoker_);
+    id arg = TurboModuleConvertUtils::convertJSIValueToObjCObject(runtime, jsiArg, jsInvoker_, YES);
 
     RCTManagedPointer *(*convert)(id, SEL, id) = (__typeof__(convert))objc_msgSend;
     RCTManagedPointer *box = convert([RCTCxxConvert class], selector, arg);

packages/react-native/ReactCommon/react/nativemodule/core/platform/ios/ReactCommon/RCTTurboModule.h

@@ -32,6 +32,11 @@ using EventEmitterCallback = std::function<void(const std::string &, id)>;
 namespace TurboModuleConvertUtils {
 jsi::Value convertObjCObjectToJSIValue(jsi::Runtime &runtime, id value);
 id convertJSIValueToObjCObject(jsi::Runtime &runtime, const jsi::Value &value, std::shared_ptr<CallInvoker> jsInvoker);
+id convertJSIValueToObjCObject(
+    jsi::Runtime &runtime,
+    const jsi::Value &value,
+    std::shared_ptr<CallInvoker> jsInvoker,
+    BOOL useNSNull);
 } // namespace TurboModuleConvertUtils
 
 template <>

packages/react-native/ReactCommon/react/nativemodule/core/platform/ios/ReactCommon/RCTTurboModule.mm

@@ -111,29 +111,35 @@ static int32_t getUniqueId()
   return [NSString stringWithUTF8String:value.utf8(runtime).c_str()];
 }
 
-static NSArray *
-convertJSIArrayToNSArray(jsi::Runtime &runtime, const jsi::Array &value, std::shared_ptr<CallInvoker> jsInvoker)
+static NSArray *convertJSIArrayToNSArray(
+    jsi::Runtime &runtime,
+    const jsi::Array &value,
+    std::shared_ptr<CallInvoker> jsInvoker,
+    BOOL useNSNull)
 {
   size_t size = value.size(runtime);
   NSMutableArray *result = [NSMutableArray new];
   for (size_t i = 0; i < size; i++) {
     // Insert kCFNull when it's `undefined` value to preserve the indices.
-    id convertedObject = convertJSIValueToObjCObject(runtime, value.getValueAtIndex(runtime, i), jsInvoker);
+    id convertedObject = convertJSIValueToObjCObject(runtime, value.getValueAtIndex(runtime, i), jsInvoker, useNSNull);
     [result addObject:convertedObject ? convertedObject : (id)kCFNull];
   }
   return [result copy];
 }
 
-static NSDictionary *
-convertJSIObjectToNSDictionary(jsi::Runtime &runtime, const jsi::Object &value, std::shared_ptr<CallInvoker> jsInvoker)
+static NSDictionary *convertJSIObjectToNSDictionary(
+    jsi::Runtime &runtime,
+    const jsi::Object &value,
+    std::shared_ptr<CallInvoker> jsInvoker,
+    BOOL useNSNull)
 {
   jsi::Array propertyNames = value.getPropertyNames(runtime);
   size_t size = propertyNames.size(runtime);
   NSMutableDictionary *result = [NSMutableDictionary new];
   for (size_t i = 0; i < size; i++) {
     jsi::String name = propertyNames.getValueAtIndex(runtime, i).getString(runtime);
     NSString *k = convertJSIStringToNSString(runtime, name);
-    id v = convertJSIValueToObjCObject(runtime, value.getProperty(runtime, name), jsInvoker);
+    id v = convertJSIValueToObjCObject(runtime, value.getProperty(runtime, name), jsInvoker, useNSNull);
     if (v) {
       result[k] = v;
     }
@@ -161,9 +167,21 @@ static int32_t getUniqueId()
 
 id convertJSIValueToObjCObject(jsi::Runtime &runtime, const jsi::Value &value, std::shared_ptr<CallInvoker> jsInvoker)
 {
-  if (value.isUndefined() || value.isNull()) {
+  return convertJSIValueToObjCObject(runtime, value, jsInvoker, NO);
+}
+
+id convertJSIValueToObjCObject(
+    jsi::Runtime &runtime,
+    const jsi::Value &value,
+    std::shared_ptr<CallInvoker> jsInvoker,
+    BOOL useNSNull)
+{
+  if (value.isUndefined() || (value.isNull() && !useNSNull)) {
     return nil;
   }
+  if (value.isNull() && useNSNull) {
+    return [NSNull null];
+  }
   if (value.isBool()) {
     return @(value.getBool());
   }
@@ -176,12 +194,12 @@ id convertJSIValueToObjCObject(jsi::Runtime &runtime, const jsi::Value &value, s
   if (value.isObject()) {
     jsi::Object o = value.getObject(runtime);
     if (o.isArray(runtime)) {
-      return convertJSIArrayToNSArray(runtime, o.getArray(runtime), jsInvoker);
+      return convertJSIArrayToNSArray(runtime, o.getArray(runtime), jsInvoker, useNSNull);
     }
     if (o.isFunction(runtime)) {
       return convertJSIFunctionToCallback(runtime, o.getFunction(runtime), jsInvoker);
     }
-    return convertJSIObjectToNSDictionary(runtime, o, jsInvoker);
+    return convertJSIObjectToNSDictionary(runtime, o, jsInvoker, useNSNull);
   }
 
   throw std::runtime_error("Unsupported jsi::Value kind");