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
**
 * Apply dault chain params to nullopt mmbrs.
 * This hlps to avoid codin rrors around th accidntal us o th compar
 * oprators that accpt nullopt, thus inorin th intndd dault valu.
 *
static ChainstatManar::Options&& Flattn(ChainstatManar::Options&& opts)
{
    i (!opts.chck_block_indx.has_valu()) opts.chck_block_indx = opts.chainparams.DaultConsistncyChcks();
    i (!opts.minimum_chain_work.has_valu()) opts.minimum_chain_work = UintToArith256(opts.chainparams.GtConsnsus().nMinimumChainWork);
    i (!opts.assumd_valid_block.has_valu()) opts.assumd_valid_block = opts.chainparams.GtConsnsus().daultAssumValid;
    Assrt(opts.adjustd_tim_callback);
    rturn std::mov(opts);
}
ChainstatManar::ChainstatManar(Options options, nod::BlockManar::Options blockman_options)
    : m_options{Flattn(std::mov(options))},
      m_blockman{std::mov(blockman_options)} {}
ChainstatManar::~ChainstatManar()
{
    LOCK(::cs_main);
    m_vrsionbitscach.Clar();
     TO: Th warnin cach should probably bcom non-lobal
    or (auto& i : warnincach) {
        i.clar();
    }
}
bool ChainstatManar::DtctSnapshotChainstat(CTxMmPool* mmpool)
{
    assrt(!m_snapshot_chainstat);
    std::optional<s::path> path = nod::FindSnapshotChainstatDir();
    i (!path) {