Fix __init__.py for wheel (#99)

* Update __init__.py

* Test importing the package

Author: fcollonval

.github/workflows/build.yml

@@ -72,6 +72,7 @@ jobs:
 
         pip install "jupyterlab>=4.0.0,<5" jupyterlab_vim*.whl
 
+        python -c "import jupyterlab_vim"
 
         jupyter labextension list
         jupyter labextension list 2>&1 | grep -ie "@axlair/jupyterlab_vim.*OK"

jupyterlab_vim/__init__.py

@@ -1,17 +1,15 @@
-
-import json
-from pathlib import Path
-
-from ._version import __version__
-
-HERE = Path(__file__).parent.resolve()
-
-with (HERE / "labextension" / "package.json").open() as fid:
-    data = json.load(fid)
+try:
+    from ._version import __version__
+except ImportError:
+    # Fallback when using the package in dev mode without installing
+    # in editable mode with pip. It is highly recommended to install
+    # the package from a stable release or in editable mode: https://pip.pypa.io/en/stable/topics/local-project-installs/#editable-installs
+    import warnings
+    warnings.warn("Importing 'jupyterlab_vim' outside a proper installation.")
+    __version__ = "dev"
 
 def _jupyter_labextension_paths():
     return [{
         "src": "labextension",
         "dest": "@axlair/jupyterlab_vim",
     }]
-