Error in references breaks subsequent hovers

Created by: Desentso

• Sourcegraph version: Sourcegraph.com
• Platform information: Windows 10, Chrome 70.0.3538.77

Steps to reproduce:

1. Open any C file on sourcegraph.com (I could only reproduce with C)
2. Hover over any function
3. Click "Find references"

Expected behavior:

It should show the correct references. After that the hover features should work normally.

Actual behavior:

References tab says "No local references found", even though there is local references on the same file Console throws error:

An error occurred when sending LSP requests to the language server, disabling this instance of the language extension (reload the page to clear this state).  
Error: method not found at sourcegraph.commands.executeCommand.then.responses

After this all hovering features stop working.