[Bug][Jupyter Widget] Error messages related to npm in the command line

**Describe the bug**
Things are working fine, but I am getting a strange error in my terminal after starting jupyter lab

**To Reproduce**
Steps to reproduce the behavior:
1. load kepler
2. Display map

**Expected behavior**

No errors in the console related to jupyterlab widget

**Screenshots**
If applicable, add screenshots to help explain your problem.


**Environment (please complete the following information):**
- Python version: python 3
- keplergl Widget version: 0.2.0

**Additional context**
Here are the error messages:

```
[W 12:11:23.410 LabApp] 404 GET /api/kernels/aaa1cf5e-ab6e-4b50-92ef-9957a3e762fa/channels?session_id=750dc446-a0ff-4fd7-9bfc-feca6cbd4838&token=442b0f104be7a193455b800d2df149180a1ce70e440fbc91 (::1): Kernel does not exist: aaa1cf5e-ab6e-4b50-92ef-9957a3e762fa
[W 12:11:23.439 LabApp] 404 GET /api/kernels/aaa1cf5e-ab6e-4b50-92ef-9957a3e762fa/channels?session_id=750dc446-a0ff-4fd7-9bfc-feca6cbd4838&token=442b0f104be7a193455b800d2df149180a1ce70e440fbc91 (::1) 32.03ms referer=None
[W 12:11:24.301 LabApp] 404 GET /api/kernels/1ae34979-1487-4fb6-8bcb-a9fd6bc29d6e/channels?session_id=99af6b94-9576-4349-ab42-1e4428046eb1&token=442b0f104be7a193455b800d2df149180a1ce70e440fbc91 (::1): Kernel does not exist: 1ae34979-1487-4fb6-8bcb-a9fd6bc29d6e
[W 12:11:24.303 LabApp] 404 GET /api/kernels/1ae34979-1487-4fb6-8bcb-a9fd6bc29d6e/channels?session_id=99af6b94-9576-4349-ab42-1e4428046eb1&token=442b0f104be7a193455b800d2df149180a1ce70e440fbc91 (::1) 3.32ms referer=None
[W 12:11:24.936 LabApp] Replacing stale connection: 1ae34979-1487-4fb6-8bcb-a9fd6bc29d6e:99af6b94-9576-4349-ab42-1e4428046eb1
[I 12:11:25.802 LabApp] 301 GET /lab/workspaces/auto-6/?clone (::1) 0.92ms
[W 12:11:26.468 LabApp] Could not determine jupyterlab build status without nodejs
[E 12:11:28.043 LabApp] Uncaught exception GET /lab/api/extensions?1589397087628 (::1)
HTTPServerRequest(protocol='http', host='localhost:8888', method='GET', uri='/lab/api/extensions?1589397087628', version='HTTP/1.1', remote_ip='::1')
Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/tornado/web.py", line 1592, in _execute
result = yield result
File "/usr/local/lib/python3.7/site-packages/tornado/gen.py", line 1133, in run
value = future.result()
File "/usr/local/lib/python3.7/site-packages/tornado/gen.py", line 1141, in run
yielded = self.gen.throw(*exc_info)
File "/usr/local/lib/python3.7/site-packages/jupyterlab/handlers/extension_manager_handler.py", line 221, in get
extensions = yield self.manager.list_extensions()
File "/usr/local/lib/python3.7/site-packages/tornado/gen.py", line 1133, in run
value = future.result()
File "/usr/local/lib/python3.7/site-packages/tornado/gen.py", line 1141, in run
yielded = self.gen.throw(*exc_info)
File "/usr/local/lib/python3.7/site-packages/jupyterlab/handlers/extension_manager_handler.py", line 91, in list_extensions
pkg_info = yield self._get_pkg_info(name, data)
File "/usr/local/lib/python3.7/site-packages/tornado/gen.py", line 1133, in run
value = future.result()
File "/usr/local/lib/python3.7/site-packages/tornado/gen.py", line 1141, in run
yielded = self.gen.throw(*exc_info)
File "/usr/local/lib/python3.7/site-packages/jupyterlab/handlers/extension_manager_handler.py", line 160, in _get_pkg_info
outdated = yield self._get_outdated()
File "/usr/local/lib/python3.7/site-packages/tornado/gen.py", line 1133, in run
value = future.result()
File "/usr/local/lib/python3.7/site-packages/tornado/gen.py", line 1141, in run
yielded = self.gen.throw(*exc_info)
File "/usr/local/lib/python3.7/site-packages/jupyterlab/handlers/extension_manager_handler.py", line 194, in _load_outdated
app_options=self.app_options
File "/usr/local/lib/python3.7/site-packages/tornado/gen.py", line 1133, in run
value = future.result()
File "/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/concurrent/futures/_base.py", line 428, in result
return self.__get_result()
File "/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/concurrent/futures/_base.py", line 384, in __get_result
raise self._exception
File "/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/concurrent/futures/thread.py", line 57, in run
result = self.fn(*self.args, **self.kwargs)
File "/usr/local/lib/python3.7/site-packages/jupyterlab/commands.py", line 541, in get_latest_compatible_package_versions
return handler.latest_compatible_package_versions(names)
File "/usr/local/lib/python3.7/site-packages/jupyterlab/commands.py", line 1682, in latest_compatible_package_versions
raise ValueError(msg % keys)
ValueError: "['keplergl-jupyter@0.2.0', '@jupyter-widgets/jupyterlab-manager@2.0.0']" is not a valid npm package
```