Attempting to host second instance prevents closing second host terminal

[patridge]

If you try to host a second site while a first site is currently hosted, the second terminal will log an exception and prevent exiting the non-working host execution.

Environment

• Windows 10
• Chloroplast v0.5.4.0

Steps

1. Host first site in one terminal with chloroplast host.
2. Try to host a second site in another terminal with chloroplast host.

Expected

Either Chloroplast tries to host the site at a different address.
Or, Chloroplast shows an error and doesn't continue executing.

Actual

Chloroplast will display a Kestrel exception and stack trace.

crit: Microsoft.AspNetCore.Server.Kestrel[0]
Unable to start Kestrel.
System.IO.IOException: Failed to bind to address http://127.0.0.1:5000: address already in use.
---> Microsoft.AspNetCore.Connections.AddressInUseException: Only one usage of each socket address (protocol/network address/port) is normally permitted.
......

And then, after a short delay, it will display a message that it is waiting to end.

Waiting for the host to be disposed. Ensure all 'IHost' instances are wrapped in 'using' blocks.

At this point, the second site terminal doesn't respond to Ctrl+C.

Even stopping the first site host doesn't allow the second terminal to end, and the whole terminal session must be killed.