Merge bitcoin/bitcoin#26738: test: add coverage for unknown wallet flag in setwalletflag

3666a06 test: add coverage for unknown wallet flag in `setwalletflag` (brunoerg)

Pull request description:

  This PR adds test coverage for the following error:
  https://github.com/bitcoin/bitcoin/blob/6d40a1a7e7f09ff2c32e53237f968adf8300d028/src/wallet/rpc/wallet.cpp#L275-L277

  https://marcofalke.github.io/btc_cov/total.coverage/src/wallet/rpc/wallet.cpp.gcov.html

ACKs for top commit:
  aureleoules:
    ACK 3666a06

Tree-SHA512: b6b2415442dfbc2404aed9720cc899995686007d6ba222dae461d064e4454d5af1326d3d527770b51b1005721ac42a49972f1eabf21108f656c30d3584790747

Author: MarcoFalke

test/functional/wallet_avoidreuse.py

@@ -120,6 +120,8 @@ def test_persistence(self):
         assert_raises_rpc_error(-8, "Wallet flag is already set to false", self.nodes[0].setwalletflag, 'avoid_reuse', False)
         assert_raises_rpc_error(-8, "Wallet flag is already set to true", self.nodes[1].setwalletflag, 'avoid_reuse', True)
 
+        assert_raises_rpc_error(-8, "Unknown wallet flag: abc", self.nodes[0].setwalletflag, 'abc', True)
+
         # Create a wallet with avoid reuse, and test that disabling it afterwards persists
         self.nodes[1].createwallet(wallet_name="avoid_reuse_persist", avoid_reuse=True)
         w = self.nodes[1].get_wallet_rpc("avoid_reuse_persist")