[PATCH v2 07/12] replay: die when --onto does not peel to a commit

["Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>]

From: Johannes Schindelin <johannes.schindelin@gmx.de>

The `peel_committish()` function calls `repo_peel_to_type()` to convert
the given object to a commit, but does not check the return value. When
the object exists but cannot be peeled to a commit (e.g., a tree or blob
OID is passed as --onto), the return value is NULL. Add an explicit NULL
check and die with a descriptive message in that case.

Pointed out by Coverity.

Assisted-by: Claude Opus 4.6
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 replay.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/replay.c b/replay.c
index da531d5bc6..b38cd5efe4 100644
--- a/replay.c
+++ b/replay.c
@@ -36,12 +36,16 @@ static struct commit *peel_committish(struct repository *repo,
 {
 	struct object *obj;
 	struct object_id oid;
+	struct commit *commit;
 
 	if (repo_get_oid(repo, name, &oid))
 		die(_("'%s' is not a valid commit-ish for %s"), name, mode);
 	obj = parse_object_or_die(repo, &oid, name);
-	return (struct commit *)repo_peel_to_type(repo, name, 0, obj,
-						  OBJ_COMMIT);
+	commit = (struct commit *)repo_peel_to_type(repo, name, 0, obj,
+						    OBJ_COMMIT);
+	if (!commit)
+		die(_("'%s' does not point to a commit for %s"), name, mode);
+	return commit;
 }
 
 static char *get_author(const char *message)
-- 
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