I'm signing a keystore to upload a flutter app to google play for the first time, and having trouble finding a keystore. Any idea what could be going wrong?

Specifically, I'm getting the following error:

• Where: Build file '/Users/charl/Documents/Development/flutter_apps/twitter_drafts/android/app/build.gradle' line: 64

• What went wrong: A problem occurred evaluating project ':app'.

Could not find method keyAlias() for arguments [upload] on BuildType$AgpDecorated_Decorated{name=release, debuggable=false, testCoverageEnabled=false, jniDebuggable=false, pseudoLocalesEnabled=false, renderscriptDebuggable=false, renderscriptOptimLevel=3, minifyEnabled=true, zipAlignEnabled=true, signingConfig=null, embedMicroApp=true, mBuildConfigFields={}, mResValues={}, mProguardFiles=[/Users/charl/Documents/Development/flutter_apps/twitter_drafts/build/app/intermediates/default_proguard_files/global/proguard-android.txt-7.3.0, /Users/charl/Documents/Development/SDKs/flutter/packages/flutter_tools/gradle/flutter_proguard_rules.pro, /Users/charl/Documents/Development/flutter_apps/twitter_drafts/android/app/proguard-rules.pro], mConsumerProguardFiles=[], mManifestPlaceholders={}} of type com.android.build.gradle.internal.dsl.BuildType$AgpDecorated.

• Try:

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• Get more help at https://help.gradle.org

Here is my Build Gradle file: Build Gradle File

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

def keystoreProperties = new Properties()
def keystorePropertiesFile = rootProject.file('key.properties')
   if (keystorePropertiesFile.exists()) {
       keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
   }

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new 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 {
    namespace "com.pagefamdesigns.application_name"
    compileSdkVersion flutter.compileSdkVersion
    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 {
        applicationId "com.pagefamdesigns.application_name"
        // You can update the following values to match your application needs.
        // For more information, see: https://docs.flutter.dev/deployment/android#reviewing-the-gradle-build-configuration.
        minSdkVersion flutter.minSdkVersion
        targetSdkVersion flutter.targetSdkVersion
        versionCode 1
        versionName flutterVersionName
    }

    buildTypes {
        release {
           keyAlias keystoreProperties['keyAlias']
           keyPassword keystoreProperties['keyPassword']
           storeFile keystoreProperties['storeFile'] ? file(keystoreProperties['storeFile']) : null
           storePassword keystoreProperties['storePassword']
       }
    }
}

And here's my Key.properties file:

storePassword=[[password is here]]
keyPassword=[[password is here]]
keyAlias=upload
storeFile=/Users/charl/upload-keystore.jks

(There is a file at that location)