fix stackoverflow in constructor

[pfitzseb]

Fixes https://github.com/julia-vscode/crashreporting-issues/issues/6 (I hope).

For every PR, please check the following:

• [x] End-user documentation check. If this PR requires end-user documentation in the Julia VS Code extension docs, please add that at https://github.com/julia-vscode/docs.
• [x] Changelog mention. If this PR should be mentioned in the CHANGELOG for the Julia VS Code extension, please open a PR against https://github.com/julia-vscode/julia-vscode/blob/master/CHANGELOG.md with those changes.

[pfitzseb]

This now actually works...