added tracker nil check

config/locales/en.yml

@@ -101,3 +101,4 @@ en:
   notice_issue_not_found: "Issue not found"
   customer_details: "Customer Details"
   notice_error_project_nil: "The issue's project is nil, set project to: "
+  notice_error_tracker_nil: "The issue's tracker is nil, set tracker to: "

lib/redmine_qbo/patches/issues_controller_patch.rb

@@ -24,6 +24,11 @@ module RedmineQbo
             context[:controller].flash[:error] = I18n.t(:notice_error_project_nil) + context[:issue].project.to_s
           end
 
+          if context[:issue].tracker.nil?
+            context[:issue].tracker = trackers_for_select(context[:issue]).first
+            context[:controller].flash[:error] = I18n.t(:notice_error_tracker_nil) + context[:issue].tracker.to_s
+          end
+
           return context
         end