Image File field not getting updated
Maybe this can help How to upload file in drupal8 forms with form element type file?

I see for your use case it makes more sense to use Managed file type.

A couple of observations, something you should look at,


It seems you are getting SQL errors due to trying to upload a file which is already present in the table, you should check why this happens and perhaps programmatically change the name of the file if it already exists. See file_save_data
Errors from views, not sure where you are trying to submit this form, but it is clearly breaking something in views_data_export or it maybe because of the next point.
Lastly, check the link above for how to properly handle file uploads in form, it looks like file_save($file); is breaking for you due to missing uri