diff: assert that we're passed a valid git_diff object CID 1386176, 1386177, 1388219
diff --git a/src/diff_tform.c b/src/diff_tform.c
index 8c5abbf..3a8924d 100644
--- a/src/diff_tform.c
+++ b/src/diff_tform.c
@@ -816,6 +816,8 @@ int git_diff_find_similar(
diff_find_match *best_match;
git_diff_file swap;
+ assert(diff);
+
if ((error = normalize_find_opts(diff, &opts, given_opts)) < 0)
return error;