[0.x] Support JupyterLite 0.2.0

jupyterlite_xeus_python/env_build_addon.py

@@ -22,13 +22,16 @@
     UTF8,
     FEDERATED_EXTENSIONS,
 )
-from jupyterlite_core.addons.federated_extensions import (
-    FederatedExtensionAddon,
-    ENV_EXTENSIONS,
-)
+from jupyterlite_core.addons.federated_extensions import FederatedExtensionAddon
 
 from .build import XEUS_PYTHON_VERSION, build_and_pack_emscripten_env
 
+try:
+    # support jupyterlite-core 0.2.0
+    from jupyterlite_core.addons.federated_extensions import ENV_EXTENSIONS
+except ImportError:
+    ENV_EXTENSIONS = None
+
 JUPYTERLITE_XEUS_PYTHON = "@jupyterlite/xeus-python-kernel"
 
 
@@ -74,7 +77,8 @@ def __init__(self, *args, **kwargs):
     def post_build(self, manager):
         """yield a doit task to create the emscripten-32 env and grab anything we need from it"""
         # Install the jupyterlite-xeus-python ourselves
-        for pkg_json in self.env_extensions(ENV_EXTENSIONS):
+        env_extensions = self.labextensions_path or ENV_EXTENSIONS
+        for pkg_json in self.env_extensions(env_extensions):
             pkg_data = json.loads(pkg_json.read_text(**UTF8))
             if pkg_data.get("name") == JUPYTERLITE_XEUS_PYTHON:
                 yield from self.safe_copy_extension(pkg_json)

setup.py

@@ -59,7 +59,7 @@
     packages=setuptools.find_packages(exclude=["tests"]),
     install_requires=[
         "traitlets",
-        "jupyterlite-core>=0.1,<0.2",
+        "jupyterlite-core>=0.1,<0.3",
         "requests",
         "empack>=3.1,<4",
         "typer",