fix: add missing error variable for non-unix build constraints (#3538)

* fix: add missing error variable for non-unix build constraints

* chore: name "_" for unused parameters

---------

Co-authored-by: Elena Kolevska <elena-kolevska@users.noreply.github.com>

internal/pool/conn_check_dummy.go

@@ -2,13 +2,19 @@
 
 package pool
 
-import "net"
+import (
+	"errors"
+	"net"
+)
 
-func connCheck(conn net.Conn) error {
+// errUnexpectedRead is placeholder error variable for non-unix build constraints
+var errUnexpectedRead = errors.New("unexpected read from socket")
+
+func connCheck(_ net.Conn) error {
 	return nil
 }
 
 // since we can't check for data on the socket, we just assume there is some
-func maybeHasData(conn net.Conn) bool {
+func maybeHasData(_ net.Conn) bool {
 	return true
 }