[metacity] frame-style: suppress logically dead code defects

[Alberts Muktupāvels <muktupavels src gnome org>]

commit c8af796a472cec8692f3b3def0a7339fa329a17a
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Mar 14 20:58:41 2021 +0200

    frame-style: suppress logically dead code defects
    
    Both enumeration values are handled outside of switch.
    
    Coverity CID: #1445653

 libmetacity/meta-frame-style.c | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/libmetacity/meta-frame-style.c b/libmetacity/meta-frame-style.c
index ced565be3..12a67a0b8 100644
--- a/libmetacity/meta-frame-style.c
+++ b/libmetacity/meta-frame-style.c
@@ -535,8 +535,17 @@ meta_frame_style_set_get_style (MetaFrameStyleSet *style_set,
         case META_FRAME_STATE_TILED_RIGHT_AND_SHADED:
           styles = style_set->tiled_right_and_shaded_styles;
           break;
+
+        /* coverity[dead_error_line] */
         case META_FRAME_STATE_NORMAL:
+          g_assert_not_reached ();
+          break;
+
+        /* coverity[dead_error_line] */
         case META_FRAME_STATE_SHADED:
+          g_assert_not_reached ();
+          break;
+
         case META_FRAME_STATE_LAST:
         default:
           g_assert_not_reached ();