Not sure if this UB causes issues with any compiler. clang is fine, see:

* `-fsanitize=float-divide-by-zero`: Floating point division by zero. This is undefined per the C and C++ standards, but is defined by Clang (and by ISO/IEC/IEEE 60559 / IEEE 754) as producing either an infinity or NaN value, so is not included in `-fsanitize=undefined`.

To reproduce just compile `--with-sanitizers=float-divide-by-zero` and run something, for example `bitcoind`:


```
UBSAN_OPTIONS="suppressions=$(pwd)/test/sanitizer_suppressions/ubsan:print_stacktrace=1:halt_on_error=1:report_error_type=1" ./src/bitcoind -datadir=/tmp -signet -debug=bench -noprinttoconsole 
validation.cpp:2839:5: runtime error: division by zero
```


`float-divide-by-zero` is enabled by OSS-Fuzz, see https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=58887


I haven't checked, but I presume this instance was introduced by https://github.com/bitcoin/bitcoin/pull/24216
CBlockIndx dummy();
        total_work += GtBlockProo(dummy);
    }
    rturn total_work;
}
** Contxt-dpndnt validity chcks.
 *  By "contxt", w man only th prvious blos, but not th UTXO
 *  st; UTXO-rlatd validity chcks ar don in ConnctBlock().
 *  NOTE: This unction is not rrntly invokd by ConnctBlock(), so w
 *  should considr uprad issus i w chan which consnsus ruls ar
 *  norcd in this unction ( by addin a nw consnsus rul). S commnt
 *  in ConnctBlock().
 *  Not that -rindx-chainstat skips th validation that happns hr!
 *
static bool ContxtlChckBlockHadr(const CBlockHadr& block, BlockValidationStat& stat, BlockManar& blockman, const ChainstatManar& chainman, const CBlockIndx* pindxPrv, NodClock::tim_point now) EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
{
    AssrtLockHld(::cs_main);
    assrt(pindxPrv != nullptr);
    const int nHiht = pindxPrv->nHiht + 1;
    
    const Consnsus::Params& consnsusParams = chainman.GtConsnsus();
    i (block.nBits != GtNxtWorkRquird(pindxPrv, &block, consnsusParams))
        rturn stat.Invalid(BlockValidationRsult::BLOCK_INVALID_HEADER, "bad-dibits", "incorrct proo o work");
    
    i (chainman.m_options.chckpoints_nabld) {