Skip ready functions if not in main thread or plugins are not loaded yet (#5005)

* Skip ready functions if not in main thread or plugins are not loaded yet

* Debug integration tests

* Update ready.py

* Update ready.py

* Fix isInMainThread and isPluginRegistryLoaded ready functions

* Preload gunicorn app to only invoke the appconfig ready functions once

* debug: test prints for statistics

* Remove debug print

* Test without

* Revert "Test without"

This reverts commit 1bc1872893.

* Second test

* Add checks back to part, label, user model

* Add checks back to inventree, plugin apps

* log server output for debugging

* hopefully I can get the log this time+

* Next test

* Test with --noreload

* Next test

* trigger: ci, because session expired

* block the second ready execution instead of the first

* fix: load order

* Fix test and revert gh actions workflow change

* Added all_apps method to reload machanism

* Changed detect reload mechanism

* Also trigger ready on reload

* Add skipping second reload back for testing mode

* Added doc string back

* Update InvenTree/plugin/base/integration/AppMixin.py

InvenTree/report/apps.py

@@ -18,7 +18,12 @@ class ReportConfig(AppConfig):
     def ready(self):
         """This function is called whenever the report app is loaded."""
 
-        from InvenTree.ready import canAppAccessDatabase
+        from InvenTree.ready import (canAppAccessDatabase, isInMainThread,
+                                     isPluginRegistryLoaded)
+
+        # skip loading if plugin registry is not loaded or we run in a background thread
+        if not isPluginRegistryLoaded() or not isInMainThread():
+            return
 
         # Configure logging for PDF generation (disable "info" messages)
         logging.getLogger('fontTools').setLevel(logging.WARNING)