The Yaml language server does not work after performing autocomplete feature

[SkorikSergey]

Reproduction Steps

1. Create a workspace from the Java stack with any project and enable Yaml language server by slider on its workspace details.
2. Start the workspace.
3. Open the Preferences widget from the Profile menu.
4. From the Yaml section add yaml schema uri by the Add Schema URl button and type "kubernetes".
5. Create openshift.yaml file.
6. Type text to the file:

kind: PersistentVolume
apiVersion: v1
metadata:

7. Set cursor to the end of last line and launch autocomplete.

Actual result:
There is an error in the dev-machine terminal and the yaml language server does not work until the workspace is restarted.

OS and version:
Che 6.6.0-SNAPSHOT; Chrome 65.0; Fedora 28

Additional information:

[SkorikSergey]

Not reproduced in CHE 6.10.0.