This is being emitted with [GCC 10.2.1](https://packages.debian.org/bullseye/g++-arm-linux-gnueabihf), in some CI jobs: i.e https://github.com/bitcoin/bitcoin/pull/25972/checks?check_run_id=12423693655, or https://github.com/bitcoin/bitcoin/pull/25972/checks?check_run_id=12423693651 (where we actually turn on all our warning flags with depends builds).
```bash
In file included from test/miniscript_tests.cpp:19:
./script/miniscript.h:1197:71: error: comparison of integers of different signs: 'typename iterator_traits<int *>::difference_type' (aka 'int') and 'const uint32_t' (aka 'const unsigned int') [-Werror,-Wsign-compare]
                    return std::count(subs.begin(), subs.end(), true) >= node.k;
                           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^  ~~~~~~
test/miniscript_tests.cpp:346:34: note: in instantiation of function template specialization 'miniscript::Node<CPubKey>::IsSatisfiable<(lambda at test/miniscript_tests.cpp:346:48)>' requested here
        bool satisfiable = node->IsSatisfiable([](const Node&) { return true; });
                                 ^
1 error generated.
```

cc @darosior 
} else if (Const("thresh(", in)) {
                int next_comma = FindNextChar(in, ',');
                if (next_comma < 1) return {};
                if (!ParseInt64(std::string(in.begin(), in.begin() + next_comma), &k)) return {};
                if (k < 1) return {};
                in = in.subspan(next_comma + 1);
                
                to_parse.emplace_back(ParseContext::THRESH, 1, k);
                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
                script_size += 2 + (k > 16) + (k > 0x7f) + (k > 0x7fff) + (k > 0x7fffff);
            } else if (Const("andor(", in)) {
                to_parse.emplace_back(ParseContext::ANDOR, -1, -1);
                to_parse.emplace_back(ParseContext::CLOSE_BRACKET, -1, -1);
                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
                to_parse.emplace_back(ParseContext::COMMA, -1, -1);
                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
                to_parse.emplace_back(ParseContext::COMMA, -1, -1);
                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
                script_size += 5;
            } else {
                if (Const("and_n(", in)) {
                    to_parse.emplace_back(ParseContext::AND_N, -1, -1);
                    script_size += 5;
                } else if (Const("and_b(", in)) {
                    to_parse.emplace_back(ParseContext::AND_B, -1, -1);
                    script_size += 2;
                } else if (Const("and_v(", in)) {
                    to_parse.emplace_back(ParseContext::AND_V, -1, -1);
                    script_size += 1;
                } else if (Const("or_b(", in)) {