Paper/paper-server/patches/sources/net/minecraft/server/CustomFunctionData.patch

--- a/net/minecraft/server/CustomFunctionData.java
+++ b/net/minecraft/server/CustomFunctionData.java
@@ -37,7 +37,7 @@
     }
 
     public CommandDispatcher<CommandListenerWrapper> getDispatcher() {
-        return this.server.getCommands().getDispatcher();
+        return this.server.vanillaCommandDispatcher.getDispatcher(); // CraftBukkit
     }
 
     public void tick() {