Use group to make it easier to clean up client tasks on exit

src/server/main.zig

@@ -83,6 +83,9 @@ pub fn start(server: *Server, io: std.Io, gpa: std.mem.Allocator) !void {
     ), io, .{ .reuse_address = true });
     defer tcp_server.deinit(io);
 
+    var client_group: std.Io.Group = .init;
+    defer client_group.cancel(io);
+
     var id: usize = 0;
     // Run until SIGINT is handled, then exit gracefully
     while (true) : (id +%= 1) {
@@ -90,7 +93,7 @@ pub fn start(server: *Server, io: std.Io, gpa: std.mem.Allocator) !void {
         if (server.clients.contains(id)) continue;
         const stream = try tcp_server.accept(io);
         std.debug.print("accepted connection\n", .{});
-        _ = io.concurrent(handleConnection, .{ server, gpa, io, id, stream }) catch {
+        _ = client_group.concurrent(io, handleConnectionInfallible, .{ server, gpa, io, id, stream }) catch {
             std.debug.print("could not start concurrent handler for {d}\n", .{id});
             stream.close(io);
         };
@@ -118,6 +121,16 @@ fn removeClient(server: *Server, io: std.Io, allocator: std.mem.Allocator, id: u
     }
 }
 
+fn handleConnectionInfallible(
+    server: *Server,
+    server_allocator: std.mem.Allocator,
+    io: std.Io,
+    id: usize,
+    stream: std.Io.net.Stream,
+) void {
+    handleConnection(server, server_allocator, io, id, stream) catch {};
+}
+
 fn handleConnection(
     server: *Server,
     server_allocator: std.mem.Allocator,