RESULT_DEVELOPER_ERROR has been the bane of my existence while working on a deployment of my app. Usually this error is known for some incorrect setup of your manifest file. Either not including the tag:

<uses -permission="-permission" android:name="com.android.vending.BILLING">

Or not having your apk loaded to the market when trying to debug.

I found another way this can be a problem. In the past I had in app billing in my application. Then I removed it and that is my currently active build. I decided to put it back in... however now I continuously get that error.
The problem is, the current apk that is "active" is not implementing the Billing permission. This means that Play Market treats it as if it is invalid. After loads of fruitless research I found that simply using an only Bundle Version and Bundle Code of a previously loaded APK that did implement the Billing permission worked beautifully.
I hope this helps someone.