Build Fails in Android Studio

Task 'assembly' not found in root project 'app'.

ionic cordova build android

<?xml version="1.0" encoding="UTF-8"?>
<module type="JAVA_MODULE" version="4">

    <component name="NewModuleRootManager" inherit-compiler-output="true">
    <exclude-output/>
    <content url="file://$MODULE_DIR$"/>
    <orderEntry type="inheritedJdk"/>
    <orderEntry type="sourceFolder" forTests="false"/>
  </component>
</module>

// Top-level build file where you can add configuration options common to all sub-projects/modules.
task assembly {}
buildscript {
    repositories {
        google()
        jcenter()
    }
    dependencies {
        // NOTE: Do not place your application dependencies here; they Belong
        // in the individual module build.gradle files

        classpath'com.android.tools.build:gradle:3.3.0'
    }
}
allprojects {
    repositories {
        google()
        jcenter()
    }
    // This replacement project.properties w.r.t.build settings
    project.ext{
      defaultBuildToolsVersion="28.0.3"// String
      defaultMinSdkVersion=19// Integer-Minimum requirement is Android 4.4
      defaultTargetSdkVersion=28//Integer-We ALWAYS target the latest by default
      defaultCompileSdkVersion=28//Integer-We ALWAYS compile with the latest by default
    }
}
task clean (type: Delete) {
    delete rootProject.buildDir
}