Undefined error when refreshing apps in Cluster Explorer

See github thread here: https://github.com/rancher/rancher/issues/29828

What kind of request is this (question/bug/enhancement/feature request):
Kind: Bug

Steps to reproduce (least amount of steps as possible):
Setup a private helm repository with credentials (clientSecret) in the Cluster Explorer of a given cluster managed by Rancher.
Go to Apps & Marketplace -> Charts -> Deploy Charts, choose which repository to refresh and press the refresh button.

When pressing refresh I get a pop-up error saying undefined undefined which I can close or acknowledge with and OK button.
Other details that may be helpful:

Environment information

  • Rancher version ( rancher/rancher / rancher/server image tag or shown bottom left in the UI): Rancher 2.5.1
  • Installation option (single install/HA): HA (3 node)

Cluster information

  • Cluster type (Hosted/Infrastructure Provider/Custom/Imported): vSphere Provision Cluster or RKE
  • Machine type (cloud/VM/metal) and specifications (CPU/memory): VM
  • Kubernetes version (use kubectl version ): 1.18.9
  • Docker version (use docker version ): 19.3.8