[pigeon] Fixes crash that occurs when an object that is removed from the instance manager calls to Dart (#10552)

In the event of a hot restart, the native `InstanceManagers` are cleared. There is then a chance for a class to make a callback when it is no in the instance manager which leads to a null exception in the codec.

Part of fixing flutter/flutter#176451
Pigeon side fix for #10529

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Author: bparrishMines

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 26.1.4
+
+* [swift][kotlin] Fixes crash that occurs when an object that is removed from the instance manager
+  calls to Dart.
+
 ## 26.1.3
 
 * [dart] Fixes error from constructor parameter sharing name with attached field for a ProxyApi.

packages/pigeon/lib/src/generator_tools.dart

@@ -15,7 +15,7 @@ import 'generator.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '26.1.3';
+const String pigeonVersion = '26.1.4';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/lib/src/kotlin/kotlin_generator.dart

@@ -2241,6 +2241,18 @@ fun deepEquals(a: Any?, b: Any?): Boolean {
                         $errorClassName("ignore-calls-error", "Calls to Dart are being ignored.", "")))
                 return''');
                 },
+                addTrailingNewline: false,
+              );
+              indent.writeScoped(
+                ' else if (!pigeonRegistrar.instanceManager.containsInstance(${classMemberNamePrefix}instanceArg)) {',
+                '}',
+                () {
+                  indent.format('''
+                callback(
+                    Result.failure(
+                        $errorClassName("missing-instance-error", "Callback to `${api.name}.${method.name}` failed because native instance was not in the instance manager.", "")))
+                return''');
+                },
               );
               indent.writeln(
                 'val binaryMessenger = pigeonRegistrar.binaryMessenger',

packages/pigeon/lib/src/swift/swift_generator.dart

@@ -2692,7 +2692,26 @@ func deepHash${generatorOptions.fileSpecificClassNameComponent}(value: Any?, has
                       code: "ignore-calls-error",
                       message: "Calls to Dart are being ignored.", details: "")))
                 return''');
-          });
+          }, addTrailingNewline: false);
+
+          final String instanceArgName = _getSafeArgumentName(
+            0,
+            NamedType(name: 'pigeonInstance', type: apiAsTypeDeclaration),
+          );
+          indent.writeScoped(
+            ' else if !pigeonRegistrar.instanceManager.containsInstance($instanceArgName as AnyObject) {',
+            '}',
+            () {
+              indent.format('''
+                completion(
+                  .failure(
+                    ${_getErrorClassName(generatorOptions)}(
+                      code: "missing-instance-error",
+                      message: "Callback to `${api.name}.${method.name}` failed because native instance was not in the instance manager.", details: "")))
+                return''');
+            },
+          );
+
           indent.writeln(
             'let binaryMessenger = pigeonRegistrar.binaryMessenger',
           );

packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/ProxyApiTestApiImpls.kt

@@ -15,7 +15,7 @@ interface ProxyApiInterface
 
 @RequiresApi(25) class ClassWithApiRequirement
 
-class ProxyApiRegistrar(binaryMessenger: BinaryMessenger) :
+open class ProxyApiRegistrar(binaryMessenger: BinaryMessenger) :
     ProxyApiTestsPigeonProxyApiRegistrar(binaryMessenger) {
   override fun getPigeonApiProxyApiTestClass(): PigeonApiProxyApiTestClass {
     return ProxyApiTestClassApi(this)