fix(process): Always check ProcessState before reaping by pid

Assisted-by: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Royce Remer <royceremer@gmail.com>

Author: rremer

modules/process/command_unix.go

@@ -27,12 +27,19 @@ func (c *Cmd) onCancel() error {
 	}
 	sig := util.Iif(c.termGraceful, syscall.SIGTERM, syscall.SIGKILL)
 	if sig == syscall.SIGTERM && c.Cmd.WaitDelay > 0 {
-		pgid, delay := c.Process.Pid, c.Cmd.WaitDelay
+		delay := c.Cmd.WaitDelay
 		go func() {
 			time.Sleep(delay)
-			_ = syscall.Kill(-pgid, syscall.SIGKILL)
+			_ = c.signalProcessGroup(syscall.SIGKILL)
 		}()
 	}
-	// kill the whole process group
+	return c.signalProcessGroup(sig)
+}
+
+// signalProcessGroup sends sig to the process group, skipping if the process has already been reaped.
+func (c *Cmd) signalProcessGroup(sig syscall.Signal) error {
+	if c.Cmd.ProcessState != nil {
+		return nil
+	}
 	return syscall.Kill(-c.Process.Pid, sig)
 }