Return error code if overlay build fails

Signed-off-by: Tobias Ribizel <mail@ribizel.de>

internal/app/wwctl/overlay/build/main.go

@@ -2,6 +2,7 @@ package build
 
 import (
 	"errors"
+	"fmt"
 	"os"
 	"strings"
 
@@ -77,7 +78,7 @@ func CobraRunE(cmd *cobra.Command, args []string) error {
 	if BuildHost && controller.Warewulf.EnableHostOverlay {
 		err := overlay.BuildHostOverlay()
 		if err != nil {
-			wwlog.Warn("host overlay could not be built: %s", err)
+			return errors.New(fmt.Sprintf("host overlay could not be built: %s", err))
 		}
 	}
 
@@ -89,7 +90,7 @@ func CobraRunE(cmd *cobra.Command, args []string) error {
 		}
 
 		if err != nil {
-			wwlog.Warn("Some overlays failed to be generated: %s", err)
+			return errors.New(fmt.Sprintf("Some overlays failed to be generated: %s", err))
 		}
 	}
 	return nil