Flutter 应用程序运行无法在 null 对象上调用方法 toInteger()

我是颤振新手。我刚刚在 GitHub 上克隆了一个我必须处理的项目。因此，首先在我的 android studio 中运行该项目会给我带来以下错误：

失败：构建失败并出现异常。

• 在哪里： 构建文件 'C:\Users\19ngu\AndroidStudioProjects\damufasta\android\app\build.gradle' 行：29

• 什么地方出了错： 评估项目“:app”时出现问题。

无法对 null 对象调用 toInteger() 方法

我已经解决了依赖关系，并将项目 SDK 和模块按照检查其他响应的指示指向最新的 API。所以我期待它能够成功运行。

这是app\build.gradle 文件内容：

def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion localProperties.getProperty('flutter.compileSdkVersion').toInteger()
    ndkVersion flutter.ndkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = '1.8'
    }

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.example.damufasta"
        // You can update the following values to match your application needs.
        // For more information, see: https://docs.flutter.dev/deployment/android#reviewing-the-build-configuration.
        minSdkVersion localProperties.getProperty('flutter.minSdkVersion').toInteger()
        targetSdkVersion localProperties.getProperty('flutter.targetSdkVersion').toInteger()
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}

将最小 sdk 设置为 21 ：

minSdkVersion = 21 第 44 行 build.gradle