From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sat, 11 Apr 2020 21:38:59 -0400
Subject: [PATCH] Disable Sync Events firing Async errors during shutdown

This is how it use to behave on Paper, and this is totally destroying
the ability to try to shut the server down gracefully during the
shutdown process as events firing on the watchdog thread are throwing
errors.

This isn't an issue on Spigot

diff --git a/src/main/java/org/bukkit/plugin/SimplePluginManager.java b/src/main/java/org/bukkit/plugin/SimplePluginManager.java
index a3027c1c6109bcb20d0468f6d0cd37182bb279ea..20b4ef7a94e00d9264b8ecc126ce5853b584ea8c 100644
--- a/src/main/java/org/bukkit/plugin/SimplePluginManager.java
+++ b/src/main/java/org/bukkit/plugin/SimplePluginManager.java
@@ -595,7 +595,7 @@ public final class SimplePluginManager implements PluginManager {
         // Paper - replace callEvent by merging to below method
         if (event.isAsynchronous() && server.isPrimaryThread()) {
             throw new IllegalStateException(event.getEventName() + " may only be triggered asynchronously.");
-        } else if (!event.isAsynchronous() && !server.isPrimaryThread()) {
+        } else if (!event.isAsynchronous() && !server.isPrimaryThread() && !server.isStopping() ) {
             throw new IllegalStateException(event.getEventName() + " may only be triggered synchronously.");
         }