thread precache panicked

Hi,

While doing the precaching, Esplora crashes constantly with the following error and then restarts, recrashing with the same error...

```
2-2020-04-17T12:40:57.924+00:00 - DEBUG - updating synced tip to 0000000000000000000dd5fb56bbbefece4709189ac351334794fc83a21c935a
2-2020-04-17T12:40:58.024+00:00 - INFO - Pre-caching stats and utxo set for 13150 scripthashes
2-2020-04-17T12:40:58.027+00:00 - INFO - running pre-cache for scripthash 6576/13150
2-2020-04-17T12:40:58.027+00:00 - INFO - running pre-cache for scripthash 1/13150
2-2020-04-17T12:40:58.027+00:00 - INFO - running pre-cache for scripthash 2466/13150
2-2020-04-17T12:40:58.028+00:00 - INFO - running pre-cache for scripthash 9041/13150
2-thread 'precache-12' panicked at 'called `Result::unwrap()` on an `Err` value: Custom("invalid length 64, expected 32")', src/new_index/schema.rs:611:22
2-stack backtrace:
2-thread 'precache-1' panicked at 'called `Result::unwrap()` on an `Err` value: Custom("invalid length 64, expected 32")', src/new_index/schema.rs:611:22
2- 0: 0x562fd5bf0076 -
2- 1: 0x562fd599f25c -
2- 2: 0x562fd5bef8e6 -
2- 3: 0x562fd5bef5cb -
2- 4: 0x562fd5beef4f -
2- 5: 0x562fd5beeb2a -
2- 6: 0x562fd599cf00 -
2- 7: 0x562fd59a35e2 -
2- 8: 0x562fd5a04c6a -
2- 9: 0x562fd5a47e7e -
2- 10: 0x562fd5a4861b -
2- 11: 0x562fd5a480f0 -
2- 12: 0x562fd5a4861b -
2- 13: 0x562fd5a480f0 -
2- 14: 0x562fd5a4861b -
2- 15: 0x562fd5a480f0 -
2- 16: 0x562fd5a4861b -
2- 17: 0x562fd5a480f0 -
2- 18: 0x562fd5a4861b -
2- 19: 0x562fd5a480f0 -
2- 20: 0x562fd5a48b4d -
2- 21: 0x562fd5bd94e6 -
2- 22: 0x562fd5bda497 -
2- 23: 0x562fd5bd9dfd -
2- 24: 0x562fd5bfcd2e -
2- 25: 0x562fd5bfe1b8 -
2- 26: 0x7f002d850fa3 - start_thread
2- 27: 0x7f002d7674cf - clone
2- 28: 0x0 -
2-stack backtrace:
2- 0: 0x562fd5bf0076 -
2- 1: 0x562fd599f25c -
2- 2: 0x562fd5bef8e6 -
2- 3: 0x562fd5bef5cb -
2- Config { log: StdErrLog { verbosity: Trace, quiet: false, show_level: true, timestamp: Millisecond, modules: [], writer: "stderr", color_choice: Never }, network_type: Bitcoin, db_path: "/data/electrs_bitcoin_db/mainnet/mainnet", daemon_dir: "/data/bitcoin", daemon_rpc_addr: V4(127.0.0.1:8332), cookie: None, electrum_rpc_addr: V4(0.0.0.0:50001), http_addr: V4(127.0.0.1:3000), monitoring_addr: V4(0.0.0.0:4224), jsonrpc_import: false, light_mode: false, address_search: true, prevout_enabled: true, cors: None, precache_scripts: Some("/srv/explorer/popular-scripts.txt"), electrum_txs_limit: 100000 }
```

I'll check how to disable the precaching and try it...