[Python language server] The Refactor -> Rename feature does not work if py file not formatted properly

[SkorikSergey]

Reproduction Steps:

1. Create and start workspace from Python stack with console-python3-simple project.
2. Open "main.py" file from the project and add text to it(without blank line in the end of file)

def add(a, b):
    return a + b

3. Click on any variable and select Refactoring->Rename(Shift+F6) feature from context menu.
4. Change name of the variable and press ENTER.

Expected behavior:
The variable name changed

Observed behavior:
The variable was not changed.
There is "org.eclipse.che.plugin.languageserver.ide.rename.RenamePresenter
SEVERE: Cannot read property 'start' of undefined" error message in browser console.
The Rename feature will work correctly if add a blank line to the end of file or format this file by Format feature.

Che version: 6.9.0
OS and version: Fedora 28
Che install: OCP-single

Additional information:

• Problem can be reliably reproduced, doesn't happen randomly: [Yes]
• See the attachment:

Screenshots:

[tsmaeder]

Does this work for other language servers (not Java, because that does not use the same code)

[SkorikSergey]

This works on Clang and TypeScript language servers.
Not works Golang language server - #10524.

[SkorikSergey]

Not reproduced in CHE-6.14.0 SNAPSHOT.