$ gradle assembleRelease --stacktrace
:lintVitalRelease FAILED

Execution failed for task ':lintVitalRelease'.
> java.lang.NullPointerException (no error message)

Caused by: java.lang.NullPointerException
	at com.android.build.gradle.internal.NdkHandler.resolveCompileSdkVersion(NdkHandler.java:116)