Return 204 not 500 on filtered pipeline (#2230)

the error check always failed, as the custom errors did not have the
`Is(error) bool` interface implemented

backport bugfix part of  #2216

server/pipeline/create.go

@@ -66,7 +66,7 @@ func Create(ctx context.Context, _store store.Store, repo *model.Repo, pipeline
 		filtered, parseErr = checkIfFiltered(repo, pipeline, forgeYamlConfigs)
 		if parseErr == nil {
 			if filtered {
-				err := ErrFiltered{Msg: "branch does not match restrictions defined in yaml"}
+				err := ErrFiltered{Msg: "global when filter of all workflows do skip this pipeline"}
 				log.Debug().Str("repo", repo.FullName).Msgf("%v", err)
 				return nil, err
 			}

server/pipeline/errors.go

@@ -22,6 +22,14 @@ func (e ErrNotFound) Error() string {
 	return e.Msg
 }
 
+func (e ErrNotFound) Is(target error) bool {
+	_, ok := target.(ErrNotFound) //nolint:errorlint
+	if !ok {
+		_, ok = target.(*ErrNotFound) //nolint:errorlint
+	}
+	return ok
+}
+
 type ErrBadRequest struct {
 	Msg string
 }
@@ -30,6 +38,14 @@ func (e ErrBadRequest) Error() string {
 	return e.Msg
 }
 
+func (e ErrBadRequest) Is(target error) bool {
+	_, ok := target.(ErrBadRequest) //nolint:errorlint
+	if !ok {
+		_, ok = target.(*ErrBadRequest) //nolint:errorlint
+	}
+	return ok
+}
+
 type ErrFiltered struct {
 	Msg string
 }
@@ -37,3 +53,11 @@ type ErrFiltered struct {
 func (e ErrFiltered) Error() string {
 	return "ignoring hook: " + e.Msg
 }
+
+func (e *ErrFiltered) Is(target error) bool {
+	_, ok := target.(ErrFiltered) //nolint:errorlint
+	if !ok {
+		_, ok = target.(*ErrFiltered) //nolint:errorlint
+	}
+	return ok
+}