Non-existent password ref

[rtibbles]

Observed behavior

In the https://github.com/learningequality/kolibri/blob/release-v0.16.x/kolibri/plugins/setup_wizard/assets/src/views/SelectSuperAdminAccountForm.vue component, this.$refs.password is always undefined, which can give an unhandled error during certain operations.

Errors and logs

First reported here: https://github.com/learningequality/kolibri/blob/release-v0.16.x/kolibri/plugins/setup_wizard/assets/src/views/SelectSuperAdminAccountForm.vue

Expected behavior

References to non-existent refs should be removed.

User-facing consequences

Seemingly none.