From 81666bf9ac8b42d0ac25415ee3815d899c8adda6 Mon Sep 17 00:00:00 2001
From: SomberNight <somber.night@protonmail.com>
Date: Mon, 5 Mar 2018 11:44:03 +0100
Subject: [PATCH] fix #4026

---
 lib/synchronizer.py | 6 ++++++
 lib/verifier.py     | 5 ++++-
 lib/wallet.py       | 3 ++-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/synchronizer.py b/lib/synchronizer.py
index 70e13e529..4b81810db 100644
--- a/lib/synchronizer.py
+++ b/lib/synchronizer.py
@@ -84,6 +84,8 @@ class Synchronizer(ThreadJob):
         return bh2u(hashlib.sha256(status.encode('ascii')).digest())
 
     def on_address_status(self, response):
+        if self.wallet.synchronizer is None:
+            return  # we have been killed, this was just an orphan callback
         params, result = self.parse_response(response)
         if not params:
             return
@@ -98,6 +100,8 @@ class Synchronizer(ThreadJob):
             self.requested_addrs.remove(addr)
 
     def on_address_history(self, response):
+        if self.wallet.synchronizer is None:
+            return  # we have been killed, this was just an orphan callback
         params, result = self.parse_response(response)
         if not params:
             return
@@ -127,6 +131,8 @@ class Synchronizer(ThreadJob):
         self.requested_histories.pop(addr)
 
     def tx_response(self, response):
+        if self.wallet.synchronizer is None:
+            return  # we have been killed, this was just an orphan callback
         params, result = self.parse_response(response)
         if not params:
             return
diff --git a/lib/verifier.py b/lib/verifier.py
index c2d0f1250..236ffbfe6 100644
--- a/lib/verifier.py
+++ b/lib/verifier.py
@@ -65,6 +65,8 @@ class SPV(ThreadJob):
             self.undo_verifications()
 
     def verify_merkle(self, r):
+        if self.wallet.verifier is None:
+            return  # we have been killed, this was just an orphan callback
         if r.get('error'):
             self.print_error('received an error:', r)
             return
@@ -95,7 +97,8 @@ class SPV(ThreadJob):
         self.print_error("verified %s" % tx_hash)
         self.wallet.add_verified_tx(tx_hash, (tx_height, header.get('timestamp'), pos))
 
-    def hash_merkle_root(self, merkle_s, target_hash, pos):
+    @classmethod
+    def hash_merkle_root(cls, merkle_s, target_hash, pos):
         h = hash_decode(target_hash)
         for i in range(len(merkle_s)):
             item = merkle_s[i]
diff --git a/lib/wallet.py b/lib/wallet.py
index 291d63db3..28597b851 100644
--- a/lib/wallet.py
+++ b/lib/wallet.py
@@ -912,7 +912,8 @@ class Abstract_Wallet(PrintError):
                     # make tx local
                     self.unverified_tx.pop(tx_hash, None)
                     self.verified_tx.pop(tx_hash, None)
-                    self.verifier.merkle_roots.pop(tx_hash, None)
+                    if self.verifier:
+                        self.verifier.merkle_roots.pop(tx_hash, None)
                     # but remove completely if not is_mine
                     if self.txi[tx_hash] == {}:
                         # FIXME the test here should be for "not all is_mine"; cannot detect conflict in some cases