A call to `removeprunedfunds` does not update the transaction list in the GUI, and trying to access the info of a deleted transaction will result in a segfault.

```bash
(lldb) run
Process 4859 launched: '/Users/michael/github/bitcoin/src/qt/bitcoin-qt' (x86_64)
2019-09-24 15:41:53.763094+0800 bitcoin-qt[4859:390268] MessageTracer: Falling back to default whitelist
Process 4859 stopped
* thread #1, name = 'bitcoin-main', queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x34)
    frame #0: 0x00000001001c9bf6 bitcoin-qt`TransactionDesc::FormatTxStatus(wtx=0x00007ffeefbfc0e0, status=0x00007ffeefbfc0c0, inMempool=false, numBlocks=1) at transactiondesc.cpp:33:31
   30  	{
   31  	    if (!status.is_final)
   32  	    {
-> 33  	        if (wtx.tx->nLockTime < LOCKTIME_THRESHOLD)
   34  	            return tr("Open for %n more block(s)", "", wtx.tx->nLockTime - numBlocks);
   35  	        else
   36  	            return tr("Open until %1").arg(GUIUtil::dateTimeStr(wtx.tx->nLockTime));
Target 0: (bitcoin-qt) stopped.
```
* - If receiving a transaction outside a block, assign its timestamp to the
 *   current time.
 * - If receiving a block with a future timestamp, assign all its (not already
 *   known) transactions' timestamps to the current time.
 * - If receiving a block with a past timestamp, before the most recent known
 *   transaction (that we care about), assign all its (not already known)
 *   transactions' timestamps to the same timestamp as that most-recent-known
 *   transaction.
 * - If receiving a block with a past timestamp, but after the most recent known
 *   transaction, assign all its (not already known) transactions' timestamps to
 *   the block time.
 *
 * For more information see CWalletTx::nTimeSmart,
 * https:bitcointalk.org/?topic=54527, or
 * https:github.com/bitcoin/bitcoin/pull/1393.
 */
unsigned int CWallet::ComputeTimeSmart(const CWalletTx& wtx) const
{
    unsigned int nTimeSmart = wtx.nTimeReceived;
    if (!wtx.isUnconfirmed() && !wtx.isAbandoned()) {
        int64_t blocktime;
        if (chain().findBlock(wtx.m_confirm.hashBlock, nullptr , &blocktime)) {
            int64_t latestNow = wtx.nTimeReceived;
            int64_t latestEntry = 0;
            
            int64_t latestTolerated = latestNow + 300;
            const TxItems& txOrdered = wtxOrdered;
            for (auto it = txOrdered.rbegin(); it != txOrdered.rend(); ++it) {
                CWalletTx* const pwtx = it->second;
                if (pwtx == &wtx) {