@jonasschnelli wrote in #14979:
> #14573 broke < Qt5.6 compatibility due to calling the lambda version of `addAction` that was added in Qt5.6.

We currently [support](https://github.com/bitcoin/bitcoin/blob/master/doc/dependencies.md) QT >=5.2, but hardly anyone tests with that. If we make one of the Travis machines use it, we should have a better change of catching this.

See also discussion about minimum QT version in #13478 
credit += nWatchCreditCached;
        else
        {
            nWatchCreditCached = pwallet->GetCredit(*tx, ISMINE_WATCH_ONLY);
            fWatchCreditCached = true;
            credit += nWatchCreditCached;
        }
    }
    return credit;
}
CAmount CWalletTx::GetImmatureCredit(interfaces::Chain::Lock& locked_chain, bool fUseCache) const
{
    if (IsImmatureCoinBase(locked_chain) && IsInMainChain(locked_chain)) {
        if (fUseCache && fImmatureCreditCached)
            return nImmatureCreditCached;
        nImmatureCreditCached = pwallet->GetCredit(*tx, ISMINE_SPENDABLE);
        fImmatureCreditCached = true;
        return nImmatureCreditCached;
    }
    return 0;
}
CAmount CWalletTx::GetAvailableCredit(interfaces::Chain::Lock& locked_chain, bool fUseCache, const isminefilter& filter) const
{
    if (pwallet == nullptr)
        return 0;
    
    if (IsImmatureCoinBase(locked_chain))
        return 0;
    CAmount* cache = nullptr;
    bool* cache_used = nullptr;