Encountered error while processing success consumer

[WtfJoke]

Hi there

First of thank you for your work you put into this :) Appreciate it.
I use the code from master (slightly modified by replacing h2 database with postgres, not app code though, see diff master...WtfJoke:master)
From time to time I get this exception in my logs:

2020-12-03T16:09:05.490436+00:00 app[web.1]: [16:09:05.490][ForkJoinPool.commonPool-worker-3][ERROR]: net.dv8tion.jda.api.requests.RestAction: Encountered error while processing success consumer
2020-12-03T16:09:05.490439+00:00 app[web.1]: java.lang.IllegalArgumentException: Parameter specified as non-null is null: method com.shimmermare.inviteroles.role.RoleGranterService$grantRole$onSuccess$1.accept, parameter it
2020-12-03T16:09:05.490440+00:00 app[web.1]: at com.shimmermare.inviteroles.role.RoleGranterService$grantRole$onSuccess$1.accept(RoleGranterService.kt)
2020-12-03T16:09:05.490440+00:00 app[web.1]: at com.shimmermare.inviteroles.role.RoleGranterService$grantRole$onSuccess$1.accept(RoleGranterService.kt:15)
2020-12-03T16:09:05.490444+00:00 app[web.1]: at net.dv8tion.jda.api.requests.Request.lambda$onSuccess$0(Request.java:95)
2020-12-03T16:09:05.490444+00:00 app[web.1]: at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1426)
2020-12-03T16:09:05.490445+00:00 app[web.1]: at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
2020-12-03T16:09:05.490445+00:00 app[web.1]: at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
2020-12-03T16:09:05.490446+00:00 app[web.1]: at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
2020-12-03T16:09:05.490446+00:00 app[web.1]: at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
2020-12-03T16:09:05.490447+00:00 app[web.1]: at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)

I dont know which message it causes. Also I dont know exactly why the parameter it is null (since its declared as Void). Just wanted to share the bug report.

Maybe you know a possible cause :)