Using the quick add feature to create an Issue in the Boards view fails silently when offline

Summary

When using the '+' button to add an issue to a list in the Boards view, if the browser is offline, the form silently fails and the user loses the data typed in while attempting the create operation. Refreshing the page does not retry the submission. A typical example of this is when using GitLab over a VPN, where the connection may drop.

Steps to reproduce

• Navigate to the Boards view under Issues.
• Turn your network connection off to simulate lost connectivity.
• No message warns that the browser is offline.
• Click the '+' button on any list to add a new issue to that list. Type in the issue and submit.
• Submission will silently fail.

What is the current bug behavior?

• Fails to warn that the attempted Issue creation operation failed.

What is the expected correct behavior?

• Offline message warning
• Failure message when the issue create operation bombs out
• Possible use of Local Storage to cache the attempted entry for a retry when back online (with a dialog to the user)

Relevant logs and/or screenshots

Short video of the issue: GitLab_Error_Screencast_2019-11-27_11_23_22