Give extra info when the token doesn't work

modules/docs/src/Volo.Docs.Domain/Volo/Docs/GitHub/Documents/Version/BranchGithubVersionProvider.cs

@@ -1,9 +1,11 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Net;
 using System.Threading.Tasks;
 using Octokit;
 using Octokit.Internal;
+using Volo.Abp;
 using Volo.Abp.DependencyInjection;
 
 namespace Volo.Docs.GitHub.Documents.Version
@@ -12,10 +14,25 @@ namespace Volo.Docs.GitHub.Documents.Version
     {
         public async Task<List<GithubVersion>> GetVersions(string name, string repositoryName, string token)
         {
-            var client = GetGitHubClient(name, token);
-            var branches = await client.Repository.Branch.GetAll(name, repositoryName);
+            try
+            {
+                var client = GetGitHubClient(name, token);
+                var branches = await client.Repository.Branch.GetAll(name, repositoryName);
 
-            return branches.Select(b => new GithubVersion {Name = b.Name}).ToList();
+                return branches.Select(b => new GithubVersion { Name = b.Name }).ToList();
+            }
+            catch (Exception e)
+            {
+                var apiException = (Octokit.ApiException)e;
+                if (apiException.ApiError?.Message == "Bad credentials" ||
+                    apiException.StatusCode == HttpStatusCode.Unauthorized)
+                {
+                    throw new AbpException("Invalid credentials for the GitHub repository: " + name + "/" + repositoryName + ". " +
+                                           "The GitHub access token: " + token + " does not work!" + "\n\rError: " + e);
+                }
+
+                throw new AbpException("Could not get branches from GitHub repository: " + name + "/" + repositoryName + "\n\rError: " + e.Message);
+            }
         }
 
         private static GitHubClient GetGitHubClient(string name, string token)