fix(issue): reject unknown milestones in issue list and search filters

Gitea drops milestone filter values it cannot resolve and lists every
issue when none is left, so tea issue list --milestone nope printed all
issues and exited 0, and a pipeline closing the result would act on all
of them. issue list and search issue|pr -R now resolve each --milestone
value by ID or title and fail with "milestone "nope" not found in
alice/project". Instance-wide search cannot check the names and says so
on stderr.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/discussion_search.go

@@ -37,6 +37,10 @@ func (a *application) discussionSearchCommand(pulls bool) *cobra.Command {
 		if err != nil {
 			return err
 		}
+		milestones, err := nameFilter("milestone", opts.Milestones)
+		if err != nil {
+			return err
+		}
 		target, err := a.resolve(cmd.Context(), false)
 		if err != nil {
 			return err
@@ -50,13 +54,15 @@ func (a *application) discussionSearchCommand(pulls bool) *cobra.Command {
 		if opts.Team != "" && target.Repo != "" {
 			return clierr.Wrap(clierr.Usage, errors.New("--team requires instance-wide search; omit --repo or TEA_REPO"))
 		}
-		if len(labelNames) > 0 {
-			if target.Repo != "" {
-				if err := (services.Labels{Client: target.client, Repository: target.Repo}).RequireFilterNames(cmd.Context(), labelNames); err != nil {
-					return err
-				}
+		if target.Repo != "" {
+			if opts.Labels, opts.Milestones, err = issueFilters(cmd, target, labelNames, milestones); err != nil {
+				return err
+			}
+		} else if len(labelNames)+len(milestones) > 0 {
+			opts.Labels, opts.Milestones = strings.Join(labelNames, ","), strings.Join(milestones, ",")
+			if _, err := fmt.Fprintln(cmd.ErrOrStderr(), "warning: instance-wide search ignores --label and --milestone values that match nothing; pass --repo to check them"); err != nil {
+				return err
 			}
-			opts.Labels = strings.Join(labelNames, ",")
 		}
 		opts.Query = strings.Join(args, " ")
 		items, err := (services.Issues{Client: target.client, Repository: target.Repo}).Search(cmd.Context(), opts)