我正在使用Android Studio 2.1.2并且可以使用标准工具链进行构建，但是在启用jack时：
jackOptions {
enabled true
}
我明白了：
* What went wrong:
Execution failed for task ':app:jillDebugPackagedLibraries'.
> com.android.jill.JillException
* Try:
Run with --info or --debug option to get more log output.
Caused by: java.lang.NullPointerException
at com.android.jill.frontend.java.MethodBodyWriter.typeToUntypedDesc(MethodBodyWriter.java:2971)
at com.android.jill.frontend.java.MethodBodyWriter.getUnnamedLocalId(MethodBodyWriter.java:2923)
at com.android.jill.frontend.java.MethodBodyWriter.getLocalVariable(MethodBodyWriter.java:2909)
at com.android.jill.frontend.java.MethodBodyWriter.writeLocalAccess(MethodBodyWriter.java:2479)
at com.android.jill.frontend.java.MethodBodyWriter.writeInsn(MethodBodyWriter.java:1048)
at com.android.jill.frontend.java.MethodBodyWriter.writeBody(MethodBodyWriter.java:567)
at com.android.jill.frontend.java.MethodBodyWriter.writeJavaMethodBody(MethodBodyWriter.java:464)
at com.android.jill.frontend.java.MethodBodyWriter.writeMethodBody(MethodBodyWriter.java:404)
at com.android.jill.frontend.java.MethodBodyWriter.writeMethod(MethodBodyWriter.java:332)
at com.android.jill.frontend.java.MethodBodyWriter.write(MethodBodyWriter.java:259)
at com.android.jill.frontend.java.ClassNodeWriter.writeMethods(ClassNodeWriter.java:305)
at com.android.jill.frontend.java.ClassNodeWriter.writeClass(ClassNodeWriter.java:106)
at com.android.jill.frontend.java.ClassNodeWriter.write(ClassNodeWriter.java:69)
at com.android.jill.frontend.java.JavaTransformer.transform(JavaTransformer.java:291)
at com.android.jill.frontend.java.JavaTransformer.transformToZip(JavaTransformer.java:250)
at com.android.jill.frontend.java.JavaTransformer.transformJavaFiles(JavaTransformer.java:232)
at com.android.jill.frontend.java.JavaTransformer.transform(JavaTransformer.java:161)
... 7 more
有没有其他人看过这个，如果有，这是如何解决的？