fix: propagate repository completion API errors

pkg/github/repository_resource_completions.go

@@ -154,7 +154,10 @@ func completeBranch(ctx context.Context, client *github.Client, resolved map[str
 	if owner == "" || repo == "" {
 		return values, errors.New("owner or repo not specified")
 	}
-	branches, _, _ := client.Repositories.ListBranches(ctx, owner, repo, nil)
+	branches, _, err := client.Repositories.ListBranches(ctx, owner, repo, nil)
+	if err != nil {
+		return nil, err
+	}
 
 	for _, branch := range branches {
 		if argValue == "" || strings.HasPrefix(branch.GetName(), argValue) {
@@ -174,7 +177,10 @@ func completeSHA(ctx context.Context, client *github.Client, resolved map[string
 	if owner == "" || repo == "" {
 		return values, errors.New("owner or repo not specified")
 	}
-	commits, _, _ := client.Repositories.ListCommits(ctx, owner, repo, nil)
+	commits, _, err := client.Repositories.ListCommits(ctx, owner, repo, nil)
+	if err != nil {
+		return nil, err
+	}
 
 	for _, commit := range commits {
 		sha := commit.GetSHA()
@@ -194,7 +200,10 @@ func completeTag(ctx context.Context, client *github.Client, resolved map[string
 	if owner == "" || repo == "" {
 		return nil, errors.New("owner or repo not specified")
 	}
-	tags, _, _ := client.Repositories.ListTags(ctx, owner, repo, nil)
+	tags, _, err := client.Repositories.ListTags(ctx, owner, repo, nil)
+	if err != nil {
+		return nil, err
+	}
 	var values []string
 	for _, tag := range tags {
 		if argValue == "" || strings.Contains(tag.GetName(), argValue) {

pkg/github/repository_resource_completions_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net/http"
 	"testing"
 
 	"github.com/google/go-github/v92/github"
@@ -169,6 +170,36 @@ func TestCompleteTag_MissingDependencies(t *testing.T) {
 	assert.Nil(t, result)
 }
 
+func TestCompleteRepositoryRefs_PropagatesListErrors(t *testing.T) {
+	tests := []struct {
+		name     string
+		endpoint EndpointPattern
+		complete CompleteHandler
+	}{
+		{name: "branch", endpoint: GetReposBranchesByOwnerByRepo, complete: completeBranch},
+		{name: "commit", endpoint: GetReposCommitsByOwnerByRepo, complete: completeSHA},
+		{name: "tag", endpoint: GetReposTagsByOwnerByRepo, complete: completeTag},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			httpClient := NewMockedHTTPClient(WithRequestMatchHandler(tt.endpoint, func(w http.ResponseWriter, r *http.Request) {
+				mockResponse(t, http.StatusForbidden, map[string]string{"message": "rate limited"})(w, r)
+			}))
+			client := mustNewGHClient(t, httpClient)
+
+			values, err := tt.complete(t.Context(), client, map[string]string{
+				"owner": "octocat",
+				"repo":  "hello-world",
+			}, "")
+
+			require.Error(t, err)
+			assert.Nil(t, values)
+			assert.Contains(t, err.Error(), "rate limited")
+		})
+	}
+}
+
 func TestCompletePRNumber_MissingDependencies(t *testing.T) {
 	ctx := t.Context()