Language Server 0.2.16 crashes (Request textDocument/completion failed.)

[tomrunia]

Because earlier versions of LS have a memory leak (#450) I decided to upgrade to version 0.2.16 following the comment in the issue thread. However, version 0.2.16 crashes almost immediatly.

Steps to Reproduce

1. Open a new file in VSCode
2. Save the file, e.g. bugreport.py
3. Type some Python code, I wrote import numpy as np
4. Crash:

[Info  - 1:30:47 PM] Microsoft Python Language Server version 0.2.16.0
[Info  - 1:30:47 PM] Initializing for /usr/bin/python3.7
[Error - 1:30:48 PM] Request textDocument/completion failed.
  Message: Specified argument was out of the range of valid values.
Parameter name: index
  Code: -32000 
   at System.Char.IsLetter(String s, Int32 index)
   at Microsoft.Python.LanguageServer.Completion.CompletionItemSource.CreateCompletionItem(String text, CompletionItemKind kind)
   at System.Linq.Enumerable.SelectEnumerableIterator`2.ToArray()
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at Microsoft.Python.LanguageServer.Completion.ImportCompletion.TryGetCompletions(ImportStatement import, CompletionContext context)
   at Microsoft.Python.LanguageServer.Completion.CompletionSource.GetCompletions(IDocumentAnalysis analysis, SourceLocation location)
   at Microsoft.Python.LanguageServer.Implementation.Server.Completion(CompletionParams params, CancellationToken cancellationToken)
   at Microsoft.Python.LanguageServer.Implementation.LanguageServer.Completion(JToken token, CancellationToken cancellationToken)

VSCode Setup:

Version: 1.31.1
Commit: 1b8e8302e405050205e69b59abb3559592bb9e60
Date: 2019-02-12T02:19:29.629Z
Electron: 3.1.2
Chrome: 66.0.3359.181
Node.js: 10.2.0
V8: 6.6.346.32
OS: Linux x64 4.13.0-26-generic

Python Setup:

• virtualenv with Python 3.7
• system version of Python