title: A problem occurred evaluating project ':app'. > path may not be null or empty string. path='null'
body: <p>Iam facing error while iam trying to run flutter.</p>
  
  <pre><code> D:\fluttapp\testbuild&gt;flutter run
  Launching lib/main.dart on Google Pixel 2 XL in debug mode...
  Initializing gradle...                                       2.1s
  Resolving dependencies...
  * Error running Gradle:
  ProcessException: Process "D:\fluttapp\testbuild\android\gradlew.bat" exited abnormally:
  
  FAILURE: Build failed with an exception.
  
  * Where:
  Build file 'D:\fluttapp\testbuild\android\app\build.gradle' line: 57
  
  * What went wrong:
  A problem occurred evaluating project ':app'.
  &gt; path may not be null or empty string. path='null'
  
  * Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to
  get more log output. Run with --scan to get full insights.
  
  * Get more help at https://help.gradle.org
  
  BUILD FAILED in 6s
    Command: D:\fluttapp\testbuild\android\gradlew.bat app:properties
  
  
  Please review your Gradle project setup in the android/ folder.
  
  D:\fluttapp\testbuild&gt;flutter doctor -v
  [√] Flutter (Channel beta, v1.1.8, on Microsoft Windows [Version 10.0.17134.556], locale
      en-IN)
      • Flutter version 1.1.8 at D:\flutter
      • Framework revision 985ccb6d14 (3 weeks ago), 2019-01-08 13:45:55 -0800
      • Engine revision 7112b72cc2
      • Dart version 2.1.1 (build 2.1.1-dev.0.1 ec86471ccc)
  
  [√] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
      • Android SDK at D:\Users\Bhanu\AppData\Local
      • Android NDK location not configured (optional; useful for native profiling support)
      • Platform android-28, build-tools 28.0.3
      • ANDROID_HOME = D:\Users\Bhanu\AppData\Local
      • Java binary at: D:\Program Files\Android\Android Studio\jre\bin\java
      • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b02)
      • All Android licenses accepted.
  
  [√] Android Studio (version 3.1)
      • Android Studio at D:\Program Files\Android\Android Studio
      • Flutter plugin version 29.0.1
      • Dart plugin version 173.4700
      • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b02)
  
  [√] Connected device (1 available)
      • Google Pixel 2 XL • 192.168.50.101:5555 • android-x86 • Android 9 (API 28)
  
  • No issues found!
  </code></pre>
  
  <p>I have add repo here. I have taken sample code to make release app version but unable to generate them. Key store is created and add to code repo </p>
  
  <p><a href="https://github.com/bhanu888/buildapk" rel="noreferrer">https://github.com/bhanu888/buildapk</a></p>