create_student_teams fails and quits for nonexisting users

[Soly]

teachers_pet doesn't fail gracefully for nonexisting users.
This issue probably exists for some other commands too.

My current workaround for create_student_teams is this, which just catches the error and continues.

--- a/lib/teachers_pet/client_decorator.rb
+++ b/lib/teachers_pet/client_decorator.rb
@@ -52,8 +52,12 @@ module TeachersPet
             puts " -> @#{username} is already on @#{organization}/#{team[:name]}"
           else
             # https://github.com/octokit/octokit.rb/pull/518
-            self.add_team_membership(team[:id], username, accept: 'application/vnd.github.the-wasp-preview+json')
-            puts " -> @#{username} has been added to @#{organization}/#{team[:name]}"
+            begin
+              self.add_team_membership(team[:id], username, accept: 'application/vnd.github.the-wasp-preview+json')
+              puts " -> @#{username} has been added to @#{organization}/#{team[:name]}"
+            rescue
+              puts " -> Error adding user to team. #{username} might not exist."
+            end
           end
         end
       end