Handle errors with brackets and dialog boxes

[hyperrealgopher]

Here's an incomplete listing:

• History index error
• Incorrect starting args
• Invalid line selection
• Network errors

Can grep to view all error lines, as well, which generally should be handled with an error dialog box.

[hyperrealgopher]

Maybe break this into separate issues.

[hyperrealgopher]

Might be good to even implement this with #72 or even #73

[hyperrealgopher]

I get this error when trying to open a bogus URL:

waffle: Network.Socket.getAddrInfo (called with preferred socket type/protocol: AddrInfo {addrFlags = [AI_ADDRCONFIG], addrFamily = AF_UNSPEC, addrSocketType = Stream, addrProtocol = 0, addrAddress = , addrCanonName = }, host name: Just "gopher.oop", service name: Just "70"): does not exist (Name or service not known)
should error popup or in status? i think popover...

May have to use connectSock and closeSock myself because it automatically handles exceptions and closes the connection and progresses as normal, which is very bad! https://hackage.haskell.org/package/network-simple-0.4.0.5/docs/Network-Simple-TCP.html