Suggested by @MarcoFalke after #14627 and possibly #14420. We should warn if an unrecognised/incorrect section is present in bitcoin.conf. i.e `[testnet]` is present instead of `[test]`.
pblocktree.reset();
                pblocktree.reset(new CBlockTreeDB(nBlockTreeDBCache, false, fReset));
                if (fReset) {
                    pblocktree->WriteReindexing(true);
                    
                    if (fPruneMode)
                        CleanupBlockRevFiles();
                }
                if (ShutdownRequested()) break;
                
                
                
                
                if (!LoadBlockIndex(chainparams)) {
                    strLoadError = _("Error loading block database");
                    break;
                }
                
                
                if (!mapBlockIndex.empty() && !LookupBlockIndex(chainparams.GetConsensus().hashGenesisBlock)) {
                    return InitError(_("Incorrect or no genesis block found. Wrong datadir for network?"));
                }
                
                
                if (fHavePruned && !fPruneMode) {
                    strLoadError = _("You need to rebuild the database using -reindex to go back to unpruned mode.  This will redownload the entire blockchain");
                    break;
                }