fix: avoid retaining dev settings during bundle load

Author: janicduplessis

packages/react-native/ReactCommon/react/runtime/iostests/RCTInstanceTests.mm

@@ -8,6 +8,7 @@
 #import <XCTest/XCTest.h>
 
 #import <OCMock/OCMock.h>
+#import <React/RCTAssert.h>
 #import <React/RCTBridgeModule.h>
 #import <React/RCTBundleManager.h>
 #import <React/RCTJavaScriptLoader.h>
@@ -202,23 +203,34 @@ - (void)testInstantiatesRequestedModuleOnMainQueue
   [instance invalidate];
 }
 
-- (void)testInitializesDevSettingsBeforeLoadingBundle
+- (void)testInitializesDevSettingsAfterBundleLoadFailure
 {
   OCMStub([_mockDelegate unstableModulesRequiringMainQueueSetup]).andReturn(@[]);
 
   XCTestExpectation *loadStarted = [self expectationWithDescription:@"bundle load started"];
-  __block NSUInteger initializeCountAtBundleLoad = 0;
+  __block RCTSourceLoadBlock loadComplete;
   OCMStub([_mockDelegate loadBundleAtURL:[OCMArg any] onProgress:[OCMArg any] onComplete:[OCMArg any]])
-      .andDo(^(NSInvocation *_) {
-        initializeCountAtBundleLoad = [FakeDevSettings.initCounts countForObject:FakeDevSettingsInitialize];
+      .andDo(^(NSInvocation *invocation) {
+        __unsafe_unretained RCTSourceLoadBlock completion;
+        [invocation getArgument:&completion atIndex:4];
+        loadComplete = [completion copy];
         [loadStarted fulfill];
       });
 
   RCTInstance *instance = [self makeInstance];
   [self waitForExpectations:@[ loadStarted ] timeout:5.0];
-  [instance invalidate];
 
-  XCTAssertEqual(initializeCountAtBundleLoad, 1u);
+  XCTAssertEqual([FakeDevSettings.initCounts countForObject:FakeDevSettingsInitialize], 0u);
+
+  RCTFatalHandler previousFatalHandler = RCTGetFatalHandler();
+  RCTSetFatalHandler(^(__unused NSError *error){
+  });
+  loadComplete([NSError errorWithDomain:@"RCTInstanceTests" code:1 userInfo:nil], nil);
+  RCTSetFatalHandler(previousFatalHandler);
+
+  XCTAssertEqual([FakeDevSettings.initCounts countForObject:FakeDevSettingsInitialize], 1u);
+
+  [instance invalidate];
 }
 
 - (void)testBundleLoadAwaitsMainQueueModuleSetup

packages/react-native/ReactCommon/react/runtime/platform/ios/ReactCommon/RCTInstance.mm

@@ -543,8 +543,6 @@ - (void)_loadJSBundle:(NSURL *)sourceURL
   }
 #endif
 
-  RCTDevSettings *const devSettings = (RCTDevSettings *)[_turboModuleManager moduleForName:"DevSettings"];
-
   __weak __typeof(self) weakSelf = self;
   [_delegate loadBundleAtURL:sourceURL
       onProgress:^(RCTLoadingProgress *progressData) {
@@ -565,6 +563,8 @@ - (void)_loadJSBundle:(NSURL *)sourceURL
           return;
         }
 
+        RCTDevSettings *const devSettings =
+            (RCTDevSettings *)[strongSelf->_turboModuleManager moduleForName:"DevSettings"];
         if (error) {
           [strongSelf handleBundleLoadingError:error];
           return;