Request textDocument/hover failed. Message: unknown document

[Ark-kun]

Environment data

• VS Code version: 1.28.2
• Extension version (available under the Extensions sidebar): 2018.11.0
• OS and version: Debian 9
• Python version (& distribution if applicable, e.g. Anaconda): Python 3.5.3
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): N/A

Version: 1.28.2
Commit: 7f3ce96ff4729c91352ae6def877e59c561f4850
Date: 2018-10-17T00:20:56.183Z
Electron: 2.0.9
Chrome: 61.0.3163.100
Node.js: 8.9.3
V8: 6.1.534.41
Architecture: x64

Expected behaviour

I expect mouse hovers not to cause errors.

Actual behaviour

I get errors on mouse hovers.

Steps to reproduce:

1. Open any Python file
2. Point your mouse to any part of the code.

Logs

Repeated many times:

[Error - 5:13:34 PM] Request textDocument/hover failed.
  Message: unknown document
  Code: -32000 
   at Microsoft.Python.LanguageServer.Implementation.ProjectFiles.GetEntry(Uri documentUri, Boolean throwIfMissing)
   at Microsoft.Python.LanguageServer.Implementation.ProjectFiles.GetEntry(TextDocumentIdentifier document, Nullable`1 expectedVersion, ProjectEntry& entry, PythonAst& tree)
   at Microsoft.Python.LanguageServer.Implementation.Server.Hover(TextDocumentPositionParams params, CancellationToken cancellationToken)
   at Microsoft.Python.LanguageServer.Implementation.LanguageServer.Hover(JToken token, CancellationToken cancellationToken)

[luabud]

Fixed upstream (microsoft/python-language-server#597)