Mozilla says: add-on appears to be corrupt

[mvhulten]

The issue is already reported or known issue?

• [X] I have searched the existing issues on github
• [ ] I am using the latest version

Current behavior

When installing for Firefox ESR from https://addons.mozilla.org/en-US/firefox/addon/vimmatic/, I get the message:

Installation aborted because the add-on appears to be corrupt.

I have not before seen an error like this when installing plug-ins. I do not know with whom the problem may lie.

Expected behavior

Installation of plug-in.

Steps to reproduce

1. Open https://addons.mozilla.org/en-US/firefox/addon/vimmatic/
2. Click on the button Add to Firefox

Environment

• OS: OpenBSD-current
• Browser: Firefox ESR
• Vimmatic version: 0.4.1