'Run Code (Ctrl+Alt+N)' fails when the workspace has no folder opened

- VS Code Version: 1.30.1
- OS Version: Windows_NT x64 10.0.17134
- Code Runner Version: 0.9.5

**Describe the bug**
The command 'Run Code' fails when there's a workspace open, but it has no folders opened.

**To Reproduce**
Steps to reproduce the behavior:

1. Open VS Code
2. Open or create a new Workspace, click on 'Add Folder' and add any folder to it.
3. Close all folders by right-clicking them and selecting 'Remove Folder from Workspace'
4. Try running any code with Ctrl+Alt+N

**Actual behavior**
The command seems to fail silently, but it outputs a stacktrace to 'Log (Window)' in the Output tab of the terminal window

[2019-01-07 23:57:23.564] [renderer1] [error] Cannot read property 'uri' of undefined: TypeError: Cannot read property 'uri' of undefined
at CodeManager.getWorkspaceFolder (C:\Users\raphaelnova\.vscode\extensions\formulahendry.code-runner-0.9.5\out\src\codeManager.js:149:57)
at CodeManager.initialize (C:\Users\raphaelnova\.vscode\extensions\formulahendry.code-runner-0.9.5\out\src\codeManager.js:120:38)
at CodeManager. (C:\Users\raphaelnova\.vscode\extensions\formulahendry.code-runner-0.9.5\out\src\codeManager.js:46:18)
at Generator.next ()
at __awaiter (C:\Users\raphaelnova\.vscode\extensions\formulahendry.code-runner-0.9.5\out\src\codeManager.js:7:71)
at new Promise ()
at __awaiter (C:\Users\raphaelnova\.vscode\extensions\formulahendry.code-runner-0.9.5\out\src\codeManager.js:3:12)
at CodeManager.run (C:\Users\raphaelnova\.vscode\extensions\formulahendry.code-runner-0.9.5\out\src\codeManager.js:27:16)
at vscode.commands.registerCommand (C:\Users\raphaelnova\.vscode\extensions\formulahendry.code-runner-0.9.5\out\src\extension.js:11:21)
at e._executeContributedCommand (c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:501:455)
at e.$executeContributedCommand (c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:502:6)
at t._doInvokeHandler (c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:658:837)
at t._invokeHandler (c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:658:509)
at t._receiveRequest (c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:657:126)
at t._receiveOneMessage (c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:656:59)
at c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:653:895
at c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:130:793
at e.fire (c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:133:218)
at a (c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:186:147)
at Socket.n._socketDataListener (c:\Users\raphaelnova\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\node\extensionHostProcess.js:186:368)
at emitOne (events.js:116:13)
at Socket.emit (events.js:211:7)
at addChunk (_stream_readable.js:263:12)
at readableAddChunk (_stream_readable.js:250:11)
at Socket.Readable.push (_stream_readable.js:208:10)
at Pipe.onread (net.js:594:20)