BUG: urllib3 and CellWatcher imports with JupyterLite

The urllib3 package is not available in the Pyodide distribution by
default -- just skip the import in standalone_server since we are not
using it in Pyodide anyway.

Do not use the CellWatcher with JupyterLite where we get a zmq import
error.

Author: thewtex

itkwidgets/standalone_server.py

@@ -28,7 +28,10 @@
 from ngff_zarr import detect_cli_io_backend, cli_input_to_ngff_image, ConversionBackend
 from pathlib import Path
 from urllib.parse import parse_qs, urlencode, urlparse
-from urllib3 import PoolManager, exceptions
+from .integrations.environment import ENVIRONMENT, Env
+# not available in pyodide by default
+if ENVIRONMENT is not Env.JUPYTERLITE:
+    from urllib3 import PoolManager, exceptions
 
 logging.getLogger("urllib3").setLevel(logging.ERROR)
 logging.getLogger("websocket-client").setLevel(logging.ERROR)

itkwidgets/viewer.py

@@ -22,7 +22,6 @@
     build_init_data,
     defer_for_data_render,
 )
-from .cell_watcher import CellWatcher
 from .imjoy import register_itkwasm_imjoy_codecs
 from .integrations import _detect_render_type, _get_viewer_image, _get_viewer_point_set
 from .integrations.environment import ENVIRONMENT, Env
@@ -38,7 +37,8 @@
 _viewer_count = 1
 _codecs_registered = False
 _cell_watcher = None
-if ENVIRONMENT is not Env.HYPHA:
+if not ENVIRONMENT in (Env.HYPHA, Env.JUPYTERLITE):
+    from .cell_watcher import CellWatcher
     _cell_watcher = CellWatcher() # Instantiate the singleton class right away