Open a new file in a diff editor from the GIT SCM does not open

[lmcbout]

Bug Description:

Selecting a new File in SCM GIT view (File with an "A" on the right side, not a "M" for Modified), it generates an error and the file does not open in the diff editor. If you select the same file but try to use the "Open File" instead, no error are generated. VScode open the file in the diff editor.

Steps to Reproduce:

1. Open SCM view
2. Select a new File (One with a "A", not a modified file) Or create a new file in your workspace to have this file available as a new file
3. Left Click on your mouse to open the file in a diff editor
   --> Observe the popup Dialog with the error: Git: Cannot read property 'uri' of undefined
   --> Look at VScode: It open the diff editor

THEIA

VSCODE

Additional Information

• Operating System: Ubuntu 18.04
• Theia Version: Latest
• Git + Git-UI version: 1.39.1

[lmcbout]

In addition to the description, selecting an Untracked File in SCM GIT view (File with an "U" on the right side), it generates an error. So it seems the only file we can open is the Modified files ("M") and the deleted files ("D")

[datou0412]

Open a deleted file generates an error too