Better cancelation handling

Based on this conversation with Andrew
https://ziggit.dev/t/am-i-canceling-my-std-io-group-incorrectly/13836

src/Server.zig

@@ -131,7 +131,8 @@ fn handleConnectionInfallible(
 ) !void {
     handleConnection(server, server_allocator, io, id, stream, r_buf_size, w_buf_size) catch |err| switch (err) {
         error.Canceled => return error.Canceled,
-        else => log.err("Failed processing client {d}: {any}", .{ id, err }),
+        error.ClientDisconnected => log.debug("Client {d} disconnected", .{id}),
+        else => log.err("Failed processing client {d}: {t}", .{ id, err }),
     };
 }
 
@@ -235,13 +236,9 @@ fn handleConnection(
             },
         }
     } else |err| switch (err) {
-        error.EndOfStream, error.ReadFailed => {
-            log.debug("Client {d} disconnected", .{id});
-            return error.Canceled;
-        },
-        else => {
-            return err;
-        },
+        error.EndOfStream => return error.ClientDisconnected,
+        error.ReadFailed => return reader.err.?,
+        else => |e| return e,
     }
 }