[Bug]: Import of Data Importer configuration

[KacperSkiT]

Expected behavior

When importing a configuration with the same name, it expects a validation message which says that a configuration with this name already exists, and the message can be closed.

Actual behavior

When importing a configuration with the same name, there is no validation message, in addition, the window with the progress of the configuration import crashes and no action can be performed in the panel.

In addition, an error is returned to the browser console.

Steps to reproduce

1. Export the configuration of Data Importer that already exists
2. Import the exported configuration without any changes