fix(single-instance): Check if pointer is null

[FabianLars]

fixes #2405

[github-actions]

Package Changes Through 13b9a54

There are 5 changes which include log with patch, log-js with patch, single-instance with patch, updater with patch, updater-js with patch

Planned Package Versions

The following package releases are the planned based on the context of changes in this pull request.

package	current	next
api-example	2.0.17	2.0.18
api-example-js	2.0.13	2.0.14
log	2.2.1	2.2.2
log-js	2.2.1	2.2.2
single-instance	2.2.1	2.2.2
updater	2.5.0	2.5.1
updater-js	2.5.0	2.5.1

Add another change file through the GitHub UI by following this link.

---

Read about change files or the docs at github.com/jbolda/covector