Handle invalid target when creating releases using API (#31841)

A 500 status code was thrown when passing a non-existent target to the
create release API. This snapshot handles this error and instead throws
a 404 status code.

Discovered while working on #31840.

routers/api/v1/repo/release.go

@@ -12,6 +12,7 @@ import (
 	"code.gitea.io/gitea/models/perm"
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/modules/git"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/routers/api/v1/utils"
@@ -251,6 +252,8 @@ func CreateRelease(ctx *context.APIContext) {
 				ctx.Error(http.StatusConflict, "ReleaseAlreadyExist", err)
 			} else if models.IsErrProtectedTagName(err) {
 				ctx.Error(http.StatusUnprocessableEntity, "ProtectedTagName", err)
+			} else if git.IsErrNotExist(err) {
+				ctx.Error(http.StatusNotFound, "ErrNotExist", fmt.Errorf("target \"%v\" not found: %w", rel.Target, err))
 			} else {
 				ctx.Error(http.StatusInternalServerError, "CreateRelease", err)
 			}

services/release/release.go

@@ -65,7 +65,7 @@ func createTag(ctx context.Context, gitRepo *git.Repository, rel *repo_model.Rel
 
 			commit, err := gitRepo.GetCommit(rel.Target)
 			if err != nil {
-				return false, fmt.Errorf("createTag::GetCommit[%v]: %w", rel.Target, err)
+				return false, err
 			}
 
 			if len(msg) > 0 {

tests/integration/api_releases_test.go

@@ -208,6 +208,24 @@ func TestAPICreateReleaseToDefaultBranchOnExistingTag(t *testing.T) {
 	createNewReleaseUsingAPI(t, token, owner, repo, "v0.0.1", "", "v0.0.1", "test")
 }
 
+func TestAPICreateReleaseGivenInvalidTarget(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1})
+	owner := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: repo.OwnerID})
+	session := loginUser(t, owner.LowerName)
+	token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteRepository)
+
+	urlStr := fmt.Sprintf("/api/v1/repos/%s/%s/releases", owner.Name, repo.Name)
+	req := NewRequestWithJSON(t, "POST", urlStr, &api.CreateReleaseOption{
+		TagName: "i-point-to-an-invalid-target",
+		Title:   "Invalid Target",
+		Target:  "invalid-target",
+	}).AddTokenAuth(token)
+
+	MakeRequest(t, req, http.StatusNotFound)
+}
+
 func TestAPIGetLatestRelease(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()