Merge bitcoin#29027: wallet: fix key parsing check for miniscript expressions

e1281f1 wallet: fix key parsing check for miniscript expressions in `ParseScript` (brunoerg)

Pull request description:

  In `ParseScript`, when processing miniscript expressions, the way we check for key parsing error is wrong, the actual code is unreachable because we're checking it into `if (node)` (successful parsing) statement.

ACKs for top commit:
  sipa:
    utACK e1281f1
  RandyMcMillan:
    utACK bitcoin@e1281f1
  achow101:
    ACK e1281f1

Tree-SHA512: c4b3765d32673928a1f6d84ecbaa311870da9a9625753ed15ea57c802a9f16ddafa48c1dc66c0e4be284c5862e7821ed94135498ed9b9f3d7342a080035da289

Author: achow101

src/script/descriptor.cpp

@@ -1777,15 +1777,15 @@ std::unique_ptr<DescriptorImpl> ParseScript(uint32_t& key_exp_index, Span<const
         const auto script_ctx{ctx == ParseScriptContext::P2WSH ? miniscript::MiniscriptContext::P2WSH : miniscript::MiniscriptContext::TAPSCRIPT};
         KeyParser parser(/*out = */&out, /* in = */nullptr, /* ctx = */script_ctx, key_exp_index);
         auto node = miniscript::FromString(std::string(expr.begin(), expr.end()), parser);
+        if (parser.m_key_parsing_error != "") {
+            error = std::move(parser.m_key_parsing_error);
+            return nullptr;
+        }
         if (node) {
             if (ctx != ParseScriptContext::P2WSH && ctx != ParseScriptContext::P2TR) {
                 error = "Miniscript expressions can only be used in wsh or tr.";
                 return nullptr;
             }
-            if (parser.m_key_parsing_error != "") {
-                error = std::move(parser.m_key_parsing_error);
-                return nullptr;
-            }
             if (!node->IsSane() || node->IsNotSatisfiable()) {
                 // Try to find the first insane sub for better error reporting.
                 auto insane_node = node.get();

src/test/descriptor_tests.cpp

@@ -592,9 +592,9 @@ BOOST_AUTO_TEST_CASE(descriptor_test)
     CheckUnparsable("raw(and_v(vc:andor(pk(L4gM1FBdyHNpkzsFh9ipnofLhpZRp2mwobpeULy1a6dBTvw8Ywtd),pk_k(Kx9HCDjGiwFcgVNhTrS5z5NeZdD6veeam61eDxLDCkGWujvL4Gnn),and_v(v:older(1),pk_k(L4o2kDvXXDRH2VS9uBnouScLduWt4dZnM25se7kvEjJeQ285en2A))),after(10)))", "sh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)))", "Miniscript expressions can only be used in wsh or tr.");
     CheckUnparsable("", "tr(034D2224bbbbbbbbbbcbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb40,{{{{{{{{{{{{{{{{{{{{{{multi(1,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/967808'/9,xprvA1RpRA33e1JQ7ifknakTFNpgXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/968/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/585/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/2/0/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/5/8/5/8/24/5/58/52/5/8/5/2/8/24/5/58/588/246/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/5/4/5/58/55/58/2/5/8/55/2/5/8/58/555/58/2/5/8/4//2/5/58/5w/2/5/8/5/2/4/5/58/5558'/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/8/58/2/5/58/58/2/5/8/9/588/2/58/2/5/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/82/5/8/5/5/58/52/6/8/5/2/8/{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}{{{{{{{{{DDD2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8588/246/8/5/2DLDDDDDDDbbD3DDDD/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8D)/5/2/5/58/58/2/5/58/58/58/588/2/58/2/5/8/5/25/58/58/2/5/58/58/2/5/8/9/588/2/58/2/6780,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFW/8/5/2/5/58678008')", "'multi(1,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/967808'/9,xprvA1RpRA33e1JQ7ifknakTFNpgXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/968/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/585/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/2/0/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/5/8/5/8/24/5/58/52/5/8/5/2/8/24/5/58/588/246/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/5/4/5/58/55/58/2/5/8/55/2/5/8/58/555/58/2/5/8/4//2/5/58/5w/2/5/8/5/2/4/5/58/5558'/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/8/2/5/8/5/5/8/58/2/5/58/58/2/5/8/9/588/2/58/2/5/8/5/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8/5/2/5/58/58/2/5/5/58/588/2/58/2/5/8/5/2/82/5/8/5/5/58/52/6/8/5/2/8/{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}{{{{{{{{{DDD2/5/8/5/2/5/58/58/2/5/58/58/588/2/58/2/8/5/8/5/4/5/58/588/2/6/8/5/2/8/2/5/8588/246/8/5/2DLDDDDDDDbbD3DDDD/8/2/5/8/5/2/5/58/58/2/5/5/5/58/588/2/6/8/5/2/8/2/5/8/2/58/2/5/8/5/2/8/5/8/3/4/5/58/55/2/5/58/58/2/5/5/5/8/5/2/8/5/85/2/8/2/5/8D)/5/2/5/58/58/2/5/58/58/58/588/2/58/2/5/8/5/25/58/58/2/5/58/58/2/5/8/9/588/2/58/2/6780,xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFW/8/5/2/5/58678008'' is not a valid descriptor function");
     // No uncompressed keys allowed
-    CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(049228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "A function is needed within P2WSH");
+    CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(049228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "Uncompressed keys are not allowed");
     // No hybrid keys allowed
-    CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(069228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "A function is needed within P2WSH");
+    CheckUnparsable("", "wsh(and_v(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(069228de6902abb4f541791f6d7f925b10e2078ccb1298856e5ea5cc5fd667f930eac37a00cc07f9a91ef3c2d17bf7a17db04552ff90ac312a5b8b4caca6c97aa4))),after(10)))", "Hybrid public keys are not allowed");
     // Insane at top level
     CheckUnparsable("wsh(and_b(vc:andor(pk(L4gM1FBdyHNpkzsFh9ipnofLhpZRp2mwobpeULy1a6dBTvw8Ywtd),pk_k(Kx9HCDjGiwFcgVNhTrS5z5NeZdD6veeam61eDxLDCkGWujvL4Gnn),and_v(v:older(1),pk_k(L4o2kDvXXDRH2VS9uBnouScLduWt4dZnM25se7kvEjJeQ285en2A))),after(10)))", "wsh(and_b(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)))", "and_b(vc:andor(pk(03cdabb7f2dce7bfbd8a0b9570c6fd1e712e5d64045e9d6b517b3d5072251dc204),pk_k(032707170c71d8f75e4ca4e3fce870b9409dcaf12b051d3bcadff74747fa7619c0),and_v(v:older(1),pk_k(02aa27e5eb2c185e87cd1dbc3e0efc9cb1175235e0259df1713424941c3cb40402))),after(10)) is invalid");
     // Invalid sub