Block double-submission of registration form

[nucleogenesis]

Summary

When a user double-clicks the Submit button during account creation, the subsequent requests after the first cause a database error as reported in #4779

This introduces a simple data property submitting to track if the user has submitted the form and ensures it is unset when an error occurs, reenabling the submit button.

References

Closes #4779

Reviewer guidance

1

• Open Dev Tools > Networking tab > [Filter to xhr]
• Double click the Submit button while making an account and you should only see one request made.

2

• Start over
• Trigger errors while filling out the form, then click Submit while the errors are present
• Fix the errors
• Click Submit and expect success

[Copilot]

Pull Request Overview

This PR prevents users from accidentally submitting the registration form multiple times by introducing a submitting flag and guarding the submit() method.

• Adds a submitting data property to track in‐flight submissions
• Early‐exit in submit() if a submission is already in progress
• Resets submitting on error and after the submit logic

[Copilot]

Resetting submitting immediately after dispatch call (outside of its promise handlers) allows the button to re-enable before the request completes. Move this reset into a finally block on the dispatch promise or remove this unconditional reset so the flag only clears after success or failure.

Suggested change

	this.submitting = false;
	});
	} else if (this.$refs.top.scrollIntoView) {
	this.$refs.top.scrollIntoView({ behavior: 'smooth' });
	}
	this.submitting = false;
	})
	.finally(() => {
	this.submitting = false;
	});
	} else if (this.$refs.top.scrollIntoView) {
	this.$refs.top.scrollIntoView({ behavior: 'smooth' });
	}

[Copilot]

Returning Promise.resolve() prevents callers from awaiting the actual registration request. Instead, return the this.$store.dispatch(...) promise (chained with .finally(...)) so consumers can rely on the real submission lifecycle.

Suggested change

	return Promise.resolve();
	return Promise.reject(new Error('Validation failed or agreement not accepted'));

[rtibbles]

From the issue:

We should have proper defensive checks on user creation such that attempting to create a user with a duplicate email address doesn't fail and produce a 500 error.

Need to add backend changes here to achieve the above, and also add a regression test for this behaviour.

[rtibbles]

Original issue has been unassigned, so going to close this for now.