test: add coverage for passing an invalid sighashtype

in RPCs descriptorprocesspbst, walletprocesspbst, signrawtransactionwithkey,
and signrawtransactionwithwallet.

test/functional/rpc_psbt.py

@@ -883,6 +883,9 @@ class PSBTTest(BitcoinTestFramework):
             comb_psbt = self.nodes[0].combinepsbt([psbt, parsed_psbt.to_base64()])
             assert_equal(comb_psbt, psbt)
 
+        self.log.info("Test walletprocesspsbt raises if an invalid sighashtype is passed")
+        assert_raises_rpc_error(-8, "all is not a valid sighash parameter.", self.nodes[0].walletprocesspsbt, psbt, sighashtype="all")
+
         self.log.info("Test decoding PSBT with per-input preimage types")
         # note that the decodepsbt RPC doesn't check whether preimages and hashes match
         hash_ripemd160, preimage_ripemd160 = random_bytes(20), random_bytes(50)
@@ -982,5 +985,9 @@ class PSBTTest(BitcoinTestFramework):
         rawtx = self.nodes[2].finalizepsbt(psbt)["hex"]
         self.nodes[2].sendrawtransaction(rawtx)
 
+        self.log.info("Test descriptorprocesspsbt raises if an invalid sighashtype is passed")
+        assert_raises_rpc_error(-8, "all is not a valid sighash parameter.", self.nodes[2].descriptorprocesspsbt, psbt, [descriptor], sighashtype="all")
+
+
 if __name__ == '__main__':
     PSBTTest().main()