Nullpointer Error on Alerts & Events AND Events Definition Page

While I was running 3.1.3 I had a a problem which caused massive mail flooding with alerts.
I issued the following commands to mongo

db.event_notification_status.remove({})
db.alerts.remove({})
db.event_notification_status.remove({})
db.scheduler_triggers.remove({})
db.event_processor_state.remove({})

The Alerts pages in 3.1 still loaded...

I later upgraded to 3.3 one machine at a time (I didn't make any changes to config files, issue any graylog or elasticsearch api commands (I think they are optional)
and now the pages

## Expected Behavior
Pages should load

## Current Behavior

Alerts & Events
Events Definitions

Never Load and I have the following errors in the logs

2020-06-23T12:53:49.265-04:00 ERROR [AnyExceptionClassMapper] Unhandled exception in REST resource
java.lang.NullPointerException: null
at org.graylog.events.context.EventDefinitionContextService.schedulerContext(EventDefinitionContextService.java:104) ~[graylog.jar:?]
at org.graylog.events.context.EventDefinitionContextService.contextFor(EventDefinitionContextService.java:57) ~[graylog.jar:?]
at org.graylog.events.rest.EventDefinitionsResource.list(EventDefinitionsResource.java:114) ~[graylog.jar:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_252]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_252]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_252]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_252]
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81) ~[graylog.jar:?]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144) ~[graylog.jar:?]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161) ~[graylog.jar:?]
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:205) ~[graylog.jar:?]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99) ~[graylog.jar:?]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389) ~[graylog.jar:?]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347) ~[graylog.jar:?]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102) ~[graylog.jar:?]
at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326) [graylog.jar:?]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271) [graylog.jar:?]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267) [graylog.jar:?]
at org.glassfish.jersey.internal.Errors.process(Errors.java:315) [graylog.jar:?]
at org.glassfish.jersey.internal.Errors.process(Errors.java:297) [graylog.jar:?]
at org.glassfish.jersey.internal.Errors.process(Errors.java:267) [graylog.jar:?]
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317) [graylog.jar:?]
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305) [graylog.jar:?]
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154) [graylog.jar:?]
at org.glassfish.jersey.grizzly2.httpserver.GrizzlyHttpContainer.service(GrizzlyHttpContainer.java:384) [graylog.jar:?]
at org.glassfish.grizzly.http.server.HttpHandler$1.run(HttpHandler.java:224) [graylog.jar:?]
at com.codahale.metrics.InstrumentedExecutorService$InstrumentedRunnable.run(InstrumentedExecutorService.java:181) [graylog.jar:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_252]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_252]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_252]

## Possible Solution
Maybe repair mongo indexes?

## Steps to Reproduce (for bugs)
1. Upgrade from 3.1 to 3.3 directly?
2. Erase mongod records

## Context
I can't acces alerts

## Your Environment

* Graylog Version: 3.3
* Elasticsearch Version: 6.8
* MongoDB Version: 3.6
* Operating System: Centos 7
* Browser version: Firefox LAtest