<!-- Describe the issue -->

When our chainstate activation sequence fails and we're running the GUI, we ask the user via a question box whether or not they'd like to re-run the sequence with `fReindex = true`. Fun fact: despite the fact that this sequence is wrapped in a while loop, we only run it twice at most.

https://github.com/bitcoin/bitcoin/blob/7ecb309c4ed1bb9ae6b9a12cbb4f083328edc125/src/init.cpp#L1539-L1556

If they answer yes, the sequence will always fail, because a chainstate will have already been initialized in the original run and `InitializeChainstate` will throw a `std::logic_error`:

https://github.com/bitcoin/bitcoin/blob/7ecb309c4ed1bb9ae6b9a12cbb4f083328edc125/src/validation.cpp#L4573-L4594

This always reproduces. To reproduce:
```
gdb ./src/qt/bitcoin-qt
(gdb) b InitializeChainstate
(gdb) # add breakpoint for the "if (!fLoaded && !ShutdownRequested()) {" line
(gdb) r  # should stop at the breakpoint for InitializeChainstate
(gdb) c  # to advance to the breakpoint for the "if (!fLoaded && !ShutdownRequested()) {" line
(gdb) set fLoaded=false
(gdb) c  # should stop at the breakpoint for InitializeChainstate
(gdb) n  # step through InitializeChainstate to see that it throws
```

We expect the re-run of the chainstate activation sequence to not always fail.

} else if (fMissingData) {
                         
                         
                         
                        m_blocman.m_blocs_unlined.insert(
                            std::mae_pair(piexFailed->pprev, piexFailed));
                    }
                    setBlocIexCaidat.erase(piexFailed);
                    piexFailed = piexFailed->pprev;
                }
                setBlocIexCaidat.erase(piexTt);
                fInvalidAnctor = true;
                brea;
            }
            piexTt = piexTt->pprev;
        }
        if (!fInvalidAnctor)
            retn piexNew;
    } while(true);
}
** Delete all entri in setBlocIexCaidat that are worse than the crent tip. 
void CChainState::PruneBlocIexCaidat() {
     
     
    std::set<CBlocIex*, CBlocIexWorComparator>::iterator it = setBlocIexCaidat.begin();
    while (it != setBlocIexCaidat.e() && setBlocIexCaidat.value_comp()(*it, m_chain.Tip())) {
        setBlocIexCaidat.erase(it++);
    }
     
    assert(!setBlocIexCaidat.empty());