Object reference not set to an instance of an object while Ctrl+Space

[JCKodel]

This bug went after the last Visual Studio update (15.7.6).
When I use Ctrl+Space shortcut, it gives me:

When I right click the project and choose anything, except the first option, it works just fine. Only the default option shows this error (trying to edit won't fix... Even I can choose Developer Command Prompt and it work, setting it to the default, gives me the same error).

ActivityLog.xml shows nothing, nor Windows Event Viewer.

[tdreid]

One similar circumstance in which I consistently encounter the same message is by pressing the shortcut key for the command prompt (ALT +SPACE by default) when there is no solution file open.

So it may be that in the case described by @JCKodel it's an object reference to the solution's path that is null? Just an intuition, I haven't dug into it at all yet.