Panic if RPC connection error raised

[rantan]

The tapyrus-signer daemon stop if tapyrusd RPC connection error happened.

logs

Success, daemonized
[2023-05-17T03:09:04Z TRACE tapyrus_signer::rpc] JSON-RPC request: {"method":"getblockchaininfo","params":[],"id":1,"jsonrpc":"2.0"}
[2023-05-17T03:09:04Z TRACE tapyrus_signer::rpc] JSON-RPC response: getblockchaininfo: {"result":{"aggregatePubkeys":[{"0366262690cbdf648132ce0c088962c6361112582364ede120f3780ab73438fc4b":0}],"bestblockhash":"79ea057b17b2f4b05d6433e9d19a3ef53fcc8f729d97bca768a4981e3c07476a","blocks":302668,"chain":"1939510133","headers":302668,"initialblockdownload":false,"mediantime":1684290751,"mode":"prod","pruned":false,"size_on_disk":96151958,"verificationprogress":1,"warnings":""},"error":null,"id":1,"jsonrpc":null}
[2023-05-17T03:09:04Z INFO  tapyrus_signer::signer_node] Skip waiting for ibd finish.
[2023-05-17T03:09:04Z INFO  tapyrus_signer::signer_node] Start thread for redis subscription
[2023-05-17T03:09:04Z INFO  tapyrus_signer::signer_node] Start Key generation Protocol
[2023-05-17T03:09:04Z INFO  tapyrus_signer::signer_node] Idle 5 secs...
[2023-05-17T03:09:09Z INFO  tapyrus_signer::signer_node] Start block creation rounds.
[2023-05-17T03:09:09Z TRACE tapyrus_signer::rpc] JSON-RPC request: {"method":"getblockchaininfo","params":[],"id":2,"jsonrpc":"2.0"}
[2023-05-17T03:09:09Z TRACE tapyrus_signer::timer] Start Timer name=round_timer timelimit=305s
[2023-05-17T03:09:09Z TRACE tapyrus_signer::rpc] JSON-RPC response: getblockchaininfo: {"result":null,"error":{"code":-28,"message":"Loading block index...","data":null},"id":2,"jsonrpc":null}
[2023-05-17T03:09:09Z WARN  tapyrus_signer::rpc] RPC Error: RpcError { code: -28, message: "Loading block index...", data: None }
thread 'main' panicked at 'Couldn't start the node because of an RPC connection error.', src/signer_node/mod.rs:429:21
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
[2023-05-17T03:14:14Z TRACE tapyrus_signer::timer] Stop Timer by time out name=round_timer
[2023-05-17T03:14:14Z TRACE tapyrus_signer::timer] RoundTimeoutObserverThread finished.

I think it should retry to call the RPC until the tapyrusd process wil be getting ready.