<C-o> causes popup err=RangeError message after pressing 'gd'

[fantasygiveup]

Description
I'm using the official Golang plugin on the mac machine. <C-o> combination triggers the pop-up message with the following content: ModeHandler: error handling key=<C-o>. err=RangeError. Source: Vim (extension). No other user's impact has found.

To Reproduce
Note that no custom vim settings are set up and involved.

1. Navigate the cursor and hold over some exported identified
2. Press gd. Then another source file becomes opened
3. Press <C-o>
4. See the popup error message