changing AssertionError to PoetryConsoleError

src/poetry_plugin_shell/command.py

@@ -7,6 +7,7 @@
 from typing import cast
 
 from poetry.console.commands.env_command import EnvCommand
+from poetry.console.exceptions import PoetryConsoleError
 
 
 if TYPE_CHECKING:
@@ -40,7 +41,9 @@ def handle(self) -> int:
 
         # Be sure that we have the right type of environment.
         env = self.env
-        assert env.is_venv()
+        if not env.is_venv():
+            error_msg = "Virtual environment cannot be activated"
+            raise PoetryConsoleError(error_msg)
         env = cast("VirtualEnv", env)
 
         # Setting this to avoid spawning unnecessary nested shells