page fault when block writer notifies an invalid hook with an idle event

[korli]

The original error is a pagefault. I added a check with a panic in block_cache.cpp in the function notify_transaction_listeners() just before the hook call (the check was on hook->hook being equals to 0xdeadbeef)

The session log gives details on the cache and the transaction.

[korli]

debug session

[korli]

I added the following lines for debug purposes :

+               if (hook == (void *)0xdeadbeef || !hook->hook || hook->hook == (void *)0xdeadbeef)
+                       panic("notify_transaction_listeners cache %p transaction %p, hook %p %pi, event %ld\n", cache, transaction, hook, hook->hook, event);
                hook->hook(transaction->id, event, hook->data);

[axeld]

Thanks for the info, but it's a duplicate of #2008 (as I didn't manage to fix that one correcty on first try).