https://github.com/bitcoin/bitcoin/blob/9ad6f14175c19b5d47267c3dd5840c14bad43c83/src/validation.cpp#L3711

If i'm following right the flow of the code, when we hit this lane `pindex` should be always equal to nullptr thus this check may be omitted
{
    return strprintf("CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)", nBlocks, nSize, nHeightFirst, nHeightLast, FormatISO8601Date(nTimeFirst), FormatISO8601Date(nTimeLast));
}
CBlockFileInfo* GetBlockFileInfo(size_t n)
{
    LOCK(cs_LastBlockFile);
    return &vinfoBlockFile.at(n);
}
ThresholdState VersionBitsTipState(const Consensus::Params& params, Consensus::DeploymentPos pos)
{
    LOCK(cs_main);
    return VersionBitsState(::ChainActive().Tip(), params, pos, versionbitscache);
}
BIP9Stats VersionBitsTipStatistics(const Consensus::Params& params, Consensus::DeploymentPos pos)
{
    LOCK(cs_main);
    return VersionBitsStatistics(::ChainActive().Tip(), params, pos);
}
int VersionBitsTipStateSinceHeight(const Consensus::Params& params, Consensus::DeploymentPos pos)