When using Keychain extension, double clicking on Submit on post edit form ends in an error

Steps:

• Login with Keychain
• Create a new post
• Fill in necessary fields
• Double click on the Submit button

Expected:

• Shows Keychain popup (if not configured otherwise)
• Submit the post

Actual:

• exit the post edit form
• shows a red "Unknown error" snackbar (bottom right)
• Keychain popup still appears