Index: __init__.py
===================================================================
diff -u -r5dc30de23fb46cbe81cd27dfb0359792d0a258da -r7afbecef0b9557bd33cb2612e1f813fbe480baa4
--- __init__.py	(.../__init__.py)	(revision 5dc30de23fb46cbe81cd27dfb0359792d0a258da)
+++ __init__.py	(.../__init__.py)	(revision 7afbecef0b9557bd33cb2612e1f813fbe480baa4)
@@ -3,11 +3,15 @@
 """
 import os
 
-available_plugin_folders = sorted(os.listdir('./plugins'))
+plugin_folder='./plugins'
+available_plugin_folders = sorted(os.listdir(plugin_folder))
 available_plugins = []  # to be used as global variable in the simulator
 # available_plugin_folders = (item for item in sorted(os.listdir('./plugins')) if not item.startswith("__"))
 for folder in available_plugin_folders:
-    if not folder.startswith('__') and not folder.startswith('.'):
+    folder_path = f'{plugin_folder}/{folder}'
+    if (not folder.startswith('__') and not folder.startswith('.')
+        and os.path.isdir(folder_path)
+        and os.path.isfile(f'{folder_path}/interface.ui') and os.path.isfile(f'{folder_path}/loader.py')):
         exec('from .{0}.loader import Loader as {0}'.format(folder))
         available_plugins.append(folder)
 print(*available_plugins, sep = "\n")