nbgitpuller links give 500 internal server error

In logs it says:
```
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: SingleUserLabApp - ERROR - Uncaught exception GET /jupyter/user/sverhoeven/git-pull?repo=https%3A%2F%2Fgithub.com%2FeWaterCycle%2FtechnicalPaperExampleNotebooks>
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: HTTPServerRequest(protocol='http', host='techpaperdemo.ewatercycle-nle.src.surf-hosted.nl', method='GET', uri='/jupyter/user/sverhoeven/git-pull?repo=https%3A%2>
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: Traceback (most recent call last):
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: File "/opt/conda/envs/ewatercycle/lib/python3.9/site-packages/tornado/web.py", line 1704, in _execute
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: result = await result
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: File "/opt/conda/envs/ewatercycle/lib/python3.9/site-packages/tornado/gen.py", line 216, in wrapper
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: result = ctx_run(func, *args, **kwargs)
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: File "/opt/conda/envs/ewatercycle/lib/python3.9/site-packages/nbgitpuller/handlers.py", line 175, in get
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: self.render_template(
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: File "/opt/conda/envs/ewatercycle/lib/python3.9/site-packages/notebook/base/handlers.py", line 515, in render_template
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: template = self.get_template(name)
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: File "/opt/conda/envs/ewatercycle/lib/python3.9/site-packages/nbclassic/nbserver.py", line 140, in get_template
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: return self.settings['notebook_jinja2_env'].get_template(name)
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: File "/opt/conda/envs/ewatercycle/lib/python3.9/site-packages/jinja2/environment.py", line 997, in get_template
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: return self._load_template(name, globals)
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: File "/opt/conda/envs/ewatercycle/lib/python3.9/site-packages/jinja2/environment.py", line 958, in _load_template
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: template = self.loader.load(self, name, self.make_globals(globals))
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: File "/opt/conda/envs/ewatercycle/lib/python3.9/site-packages/jinja2/loaders.py", line 125, in load
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: source, filename, uptodate = self.get_source(environment, name)
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: File "/opt/conda/envs/ewatercycle/lib/python3.9/site-packages/jinja2/loaders.py", line 214, in get_source
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: raise TemplateNotFound(template)
Jan 06 15:20:45 host-192-168-2-181 bash[41746]: jinja2.exceptions.TemplateNotFound: status.html
```

Start with nbgitpuller’s handlers.py at the logged line 175 and the missing status.html template, then inspect how the deployed Jupyter/nbclassic environment supplies templates. Reproduce the /git-pull request and confirm it no longer returns a 500 error and renders the status response.

Written by the indexing model from the issue text.