minor, tweak spacing

turn 8 spaces to tab, add space before Null/Crap
diff --git a/src/hb-open-file.hh b/src/hb-open-file.hh
index 23ca44d..2f01ce9 100644
--- a/src/hb-open-file.hh
+++ b/src/hb-open-file.hh
@@ -249,7 +249,7 @@
     switch (u.header.version.major) {
     case 2: /* version 2 is compatible with version 1 */
     case 1: return u.version1.get_face (i);
-    default:return Null(OpenTypeFontFace);
+    default:return Null (OpenTypeFontFace);
     }
   }
 
@@ -478,7 +478,7 @@
     case TrueTypeTag:	return u.fontFace;
     case TTCTag:	return u.ttcHeader.get_face (i);
     case DFontTag:	return u.rfHeader.get_face (i, base_offset);
-    default:		return Null(OpenTypeFontFace);
+    default:		return Null (OpenTypeFontFace);
     }
   }