nbgitpuller chrome extension not working when pulling branches other than main

The nbgitpuller doesn't generate the right link when pulling branches other than main. When I tried pulling [this file](https://github.com/DS-100/sp23/blob/rohan-folium-testing/lab/lab03/lab03.ipynb) to data100.datahub.berkeley.edu using the chrome extension, the load failed. However, when I manually input all the info [here](https://jupyterhub.github.io/nbgitpuller/link.html) and tried again, the pull succeeded, causing me to believe it's an issue with the chrome extension. A photo of the manual input can be seen below.

#### Expected behaviour

The link loads properly

#### Actual behaviour

The chrome extension file redirect doesn't load properly. Instead, the following error message pops up

### How to reproduce

Use the chrome extension to generate a nbgitpuller link for [this file](https://github.com/DS-100/sp23/blob/rohan-folium-testing/lab/lab03/lab03.ipynb)

### Your personal set up

- OS:
macOS 11.3.1
- Version(s):
nbgitpuller 1.1.0, jupyterhub 3.1.0, notebook==6.4.12, jupyterlab==3.4.5, python==3.9

Full environment

The full environment can be found [here](https://github.com/DS-100/datahub/blob/staging/deployments/data100/image/environment.yml) and [here](https://github.com/DS-100/datahub/blob/staging/deployments/data100/image/infra-requirements.txt).

Configuration

```python
# jupyterhub_config.py
```

Logs

```
# paste relevant logs here, if any
```