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 
JUST_0,    
    JUST_1,    
    PK_K,      
    PK_H,      
    OLDER,     
    AFTER,     
    SHA256,    
    HASH256,   
    RIPEMD160, 
    HASH160,   
    WRAP_A,    
    WRAP_S,    
    WRAP_C,    
    WRAP_D,    
    WRAP_V,    
    WRAP_J,    
    WRAP_N,    
    AND_V,     
    AND_B,     
    OR_B,      
    OR_C,      
    OR_D,      
    OR_I,      
    ANDOR,     
    THRESH,    
    MULTI,