Update #list_teams to propagate errors

app/controllers/projects/mattermosts_controller.rb

@@ -34,10 +34,7 @@ class Projects::MattermostsController < Projects::ApplicationController
   end
 
   def teams
-    @teams ||= begin
-                 teams, error_message = @service.list_teams(current_user)
-                 error_message ? error_message : teams
-               end
+    @teams, @teams_error_message = @service.list_teams(current_user)
   end
 
   def service

app/models/project_services/mattermost_slash_commands_service.rb

@@ -28,10 +28,10 @@ class MattermostSlashCommandsService < ChatSlashCommandsService
     [false, e.message]
   end
 
-  def list_teams(user)
-    Mattermost::Team.new(user).all
-  rescue Mattermost::Error
-    []
+  def list_teams(current_user)
+    [Mattermost::Team.new(current_user).all, nil]
+  rescue Mattermost::Error => e
+    [[], e.message]
   end
 
   private

app/views/projects/mattermosts/_no_teams.html.haml

@@ -1,5 +1,6 @@
-= content_for :flash_message do
-  .alert.alert-danger= @teams if @teams.is_a?(String)
+- if @teams_error_message
+  = content_for :flash_message do
+    .alert.alert-danger= @teams_error_message
 
 %p
   You aren’t a member of any team on the Mattermost instance at

app/views/projects/mattermosts/new.html.haml

@@ -2,7 +2,7 @@
   .inline.pull-right
     = custom_icon('mattermost_logo', size: 48)
   %h3 Install Mattermost Command
-  - if @teams.is_a?(String) || @teams.empty?
+  - if @teams.empty?
     = render 'no_teams'
   - else
     = render 'team_selection'

lib/mattermost/client.rb

@@ -27,12 +27,12 @@ module Mattermost
     end
 
     def json_response(response)
+      json_response = JSON.parse(response.body)
+
       unless response.success?
         raise Mattermost::ClientError.new(json_response['message'] || 'Undefined error')
       end
 
-      json_response = JSON.parse(response.body)
-
       json_response
     rescue JSON::JSONError
       raise Mattermost::ClientError.new('Cannot parse response')

spec/models/project_services/mattermost_slash_commands_service_spec.rb

@@ -113,7 +113,7 @@ describe MattermostSlashCommandsService, :models do
         end
 
         it 'shows error messages' do
-          expect(subject).to eq([])
+          expect(subject).to eq([[], "Failed to get team list."])
         end
       end
     end