list-objects-filter: use BUG rather than die

In some cases in this file, BUG makes more sense than die. In such
cases, a we get there from a coding error rather than a user error.

'return' has been removed following some instances of BUG since BUG does
not return.

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

list-objects-filter.c

@@ -44,8 +44,7 @@ static enum list_objects_filter_result filter_blobs_none(
 
 	switch (filter_situation) {
 	default:
-		die("unknown filter_situation");
-		return LOFR_ZERO;
+		BUG("unknown filter_situation: %d", filter_situation);
 
 	case LOFS_BEGIN_TREE:
 		assert(obj->type == OBJ_TREE);
@@ -102,8 +101,7 @@ static enum list_objects_filter_result filter_blobs_limit(
 
 	switch (filter_situation) {
 	default:
-		die("unknown filter_situation");
-		return LOFR_ZERO;
+		BUG("unknown filter_situation: %d", filter_situation);
 
 	case LOFS_BEGIN_TREE:
 		assert(obj->type == OBJ_TREE);
@@ -208,8 +206,7 @@ static enum list_objects_filter_result filter_sparse(
 
 	switch (filter_situation) {
 	default:
-		die("unknown filter_situation");
-		return LOFR_ZERO;
+		BUG("unknown filter_situation: %d", filter_situation);
 
 	case LOFS_BEGIN_TREE:
 		assert(obj->type == OBJ_TREE);
@@ -389,7 +386,7 @@ void *list_objects_filter__init(
 	assert((sizeof(s_filters) / sizeof(s_filters[0])) == LOFC__COUNT);
 
 	if (filter_options->choice >= LOFC__COUNT)
-		die("invalid list-objects filter choice: %d",
+		BUG("invalid list-objects filter choice: %d",
 		    filter_options->choice);
 
 	init_fn = s_filters[filter_options->choice];