Only reset completer if it exists.
Only reset completer if it exists.

charnpreetsingh185/jupyterlab,charnpreetsingh185/jupyterlab,eskirk/jupyterlab,jupyter/jupyterlab,eskirk/jupyterlab,charnpreetsingh185/jupyterlab,eskirk/jupyterlab,jupyter/jupyterlab,charnpreetsingh185/jupyterlab,eskirk/jupyterlab,eskirk/jupyterlab,jupyter/jupyterlab,charnpreetsingh185/jupyterlab,jupyter/jupyterlab,jupyter/jupyterlab