Jupyter Lab is not installed, still test.py in FRI showing {"message":"Successfuly opened Jupyter"}

To replicate this issue:- uninstalled Jupter Lab (pip3 uninstall jupyterlab)

Now run 

$ cd conore/fri

$ cd server

$ python3 main.py

and 

$ cd ..

$ python3 test.py

Expected Result:- Should throw an error.

Actual Result:- showing {"message":"Successfuly opened Jupyter"}