When web port is unavailable (already in use), Indexer still starts but in a nonfunctional mode

[robinbb]

When the port specified (or the default port of 8080) is in use, the server starts anyway after logging a crash in src/bin/mina-indexer.rs line 278. Then, the server cannot be contacted while it starts up (possibly hours), then it crashes without further error message.

Also do the same for the domain socket.