Auto Complete pops up "invalid arguments" message

[Eli-Goldberg]

An annoying warning message pops when using auto-complete (see image below)
I've disabled all extensions.

• OS Version: Ubuntu 16.04
• VSCode Version:
  Version 1.13.0-insider
  Commit cdaa5f2
  Date 2017-05-19T05:11:19.365Z

Steps to Reproduce:

1. Create new JS file and save it
2. Start typing "module" and use Tab or Enter to auto complete
3. Delete the entire word and repeat step 2
4. A warning message saying: "invalid arguments" will pop up

[mjbvz]

This is not specific to js/ts. Here's repo in a txt file:

1. Open a new text file.
2. Enable word based completions
3. Type out:

abc
ab

4. Trigger completions on on ab and the type c. Then hit tab

This shows invalid argument as well.

---

Here are the errors that I see when this happens. First:

/Users/matb/projects/vscode/out/vs/workbench/electron-browser/shell.js:268 Cannot read property 'length' of undefined: TypeError: Cannot read property 'length' of undefined
    at file:///Users/matb/projects/vscode/out/vs/editor/contrib/snippet/browser/snippetSession.js:65:101
    at Model.TextModelWithDecorations._changeDecorations (file:///Users/matb/projects/vscode/out/vs/editor/common/model/textModelWithDecorations.js:173:26)
    at Model.TextModelWithDecorations.changeDecorations (file:///Users/matb/projects/vscode/out/vs/editor/common/model/textModelWithDecorations.js:145:29)
    at OneSnippet.move (file:///Users/matb/projects/vscode/out/vs/editor/contrib/snippet/browser/snippetSession.js:57:44)
    at SnippetSession._move (file:///Users/matb/projects/vscode/out/vs/editor/contrib/snippet/browser/snippetSession.js:270:44)
    at file:///Users/matb/projects/vscode/out/vs/editor/contrib/snippet/browser/snippetSession.js:254:30
    at EditStack.pushEditOperation (file:///Users/matb/projects/vscode/out/vs/editor/common/model/editStack.js:43:87)
    at Model.EditableTextModel._pushEditOperations (file:///Users/matb/projects/vscode/out/vs/editor/common/model/editableTextModel.js:132:41)
    at Model.EditableTextModel.pushEditOperations (file:///Users/matb/projects/vscode/out/vs/editor/common/model/editableTextModel.js:59:29)
    at SnippetSession.insertNested (file:///Users/matb/projects/vscode/out/vs/editor/contrib/snippet/browser/snippetSession.js:253:39)

Which is triggered by this error using -1 to index into the placeholder groups:

The actual exception is then in setSelections in commonCodeEditor:

@jrieken Can you please take a look

[jrieken]

dupe of #26914