COPY failed: stat /var/lib/docker/tmp/docker-builder904419244/config.js: no such file or directory

**Dockerfile**
```
FROM atlassian/nucleus
COPY config.js /opt/service/config.js
```
Run
```sh
docker build -t nucleus .
```
Error info
> Sending build context to Docker daemon 2.048kB
Step 1/2 : FROM atlassian/nucleus
---> dbbbe44b8208
Step 2/2 : COPY config.js /opt/service/config.js
COPY failed: stat /var/lib/docker/tmp/docker-builder904419244/config.js: no such file or directory

Did I miss some details? BTW, I'm new to docker...

The report names the Dockerfile and the `docker build -t nucleus .` command; first inspect the build context used by that command and whether it contains `config.js`. Done means the build completes and the file is copied to `/opt/service/config.js`.

Written by the indexing model from the issue text.