[wallet] Make sure pindex is non-null before possibly referencing in LogPrintf call.

src/wallet/wallet.cpp

@@ -1544,6 +1544,10 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool f
         {
             if (pindex->nHeight % 100 == 0 && dProgressTip - dProgressStart > 0.0)
                 ShowProgress(_("Rescanning..."), std::max(1, std::min(99, (int)((GuessVerificationProgress(chainParams.TxData(), pindex) - dProgressStart) / (dProgressTip - dProgressStart) * 100))));
+            if (GetTime() >= nNow + 60) {
+                nNow = GetTime();
+                LogPrintf("Still rescanning. At block %d. Progress=%f\n", pindex->nHeight, GuessVerificationProgress(chainParams.TxData(), pindex));
+            }
 
             CBlock block;
             if (ReadBlockFromDisk(block, pindex, Params().GetConsensus())) {
@@ -1557,10 +1561,6 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool f
                 ret = nullptr;
             }
             pindex = chainActive.Next(pindex);
-            if (GetTime() >= nNow + 60) {
-                nNow = GetTime();
-                LogPrintf("Still rescanning. At block %d. Progress=%f\n", pindex->nHeight, GuessVerificationProgress(chainParams.TxData(), pindex));
-            }
         }
         if (pindex && fAbortRescan) {
             LogPrintf("Rescan aborted at block %d. Progress=%f\n", pindex->nHeight, GuessVerificationProgress(chainParams.TxData(), pindex));