Correction of a problem with wheel package.

src/appengine/__init__.py

@@ -1,6 +1,7 @@
 #!/usr/bin/python3
 
 import os
+import sys
 import traceback
 from configparser import ConfigParser
 import logging
@@ -204,6 +205,7 @@ class CommandsLoader:
     def __init__(self, config: ConfigParser, log: logging.Handler, modpath: str):
         self.config = config
         self.modpath = modpath
+        sys.path.append(os.path.join(modpath))
         Commands.defmod = self.config["general"].get("default")
         precmd = self.config["general"].get("methods_prefix")
         if not precmd is None:
@@ -242,7 +244,11 @@ class CommandsLoader:
         self.cmods = cmds
 
     def _load_module(self, name: str):
-        module = import_module(name)
+        try:
+            module = import_module(name)
+        except ModuleNotFoundError:
+            raise Exception(f"""The module "{name}" could not be loaded.""")
+
         members = inspect.getmembers(module, inspect.isclass)
         conf = None
         if name[len(self.precmds):] in self.config.sections():