fix(auth): harden unified diagnostic execution

tools/tht/internal/compose/process_unix.go

@@ -3,7 +3,6 @@
 package compose
 
 import (
-	"errors"
 	"os/exec"
 	"syscall"
 	"time"
@@ -32,6 +31,6 @@ func terminateProcess(command *exec.Cmd, done <-chan error) error {
 	case <-done:
 		return nil
 	case <-time.After(finalTerminationBound):
-		return errors.New("Docker command could not be reaped")
+		return ErrProcessReap
 	}
 }