Merge bitcoin#18853: wallet: Fix typo in assert that is compile-time …

…true

fa47cf9 wallet: Fix typo in assert that is compile-time true (MarcoFalke)

Pull request description:

  Commit 92bcd70 presumably added a check that a `dest` of type `CNoDestination` implies an empty `scriptChange`.

  However, it accidentally checked for `boost::variant::empty`, which always returns false: https://www.boost.org/doc/libs/1_72_0/doc/html/boost/variant.html#id-1_3_46_5_4_1_1_16_2-bb

ACKs for top commit:
  Sjors:
    utACK fa47cf9

Tree-SHA512: 9626b1e2947039853703932a362c2ee204e002d3344856eb93eef0e0f833401336f2dfa80fd43b83c8ec6eac624e6302aee771fb67aec436ba6483be02b8d615

src/test/script_standard_tests.cpp

@@ -12,6 +12,12 @@
 
 BOOST_FIXTURE_TEST_SUITE(script_standard_tests, BasicTestingSetup)
 
+BOOST_AUTO_TEST_CASE(dest_default_is_no_dest)
+{
+    CTxDestination dest;
+    BOOST_CHECK(!IsValidDestination(dest));
+}
+
 BOOST_AUTO_TEST_CASE(script_standard_Solver_success)
 {
     CKey keys[3];

src/wallet/wallet.cpp

@@ -3474,7 +3474,10 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CTransac
                     error = _("Transaction needs a change address, but we can't generate it. Please call keypoolrefill first.");
                 }
                 scriptChange = GetScriptForDestination(dest);
-                assert(!dest.empty() || scriptChange.empty());
+                // A valid destination implies a change script (and
+                // vice-versa). An empty change script will abort later, if the
+                // change keypool ran out, but change is required.
+                CHECK_NONFATAL(IsValidDestination(dest) != scriptChange.empty());
             }
 
             nFeeRet = 0;
@@ -3725,7 +3728,7 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CTransac
                 return false;
             }
 
-            // Give up if change keypool ran out and we failed to find a solution without change:
+            // Give up if change keypool ran out and change is required
             if (scriptChange.empty() && nChangePosInOut != -1) {
                 return false;
             }