Nextcloud helm-operator: failed to prepare chart for release: no repository definition

Job #47222 failed for 44ba3c7c:

root@flux-extra-opts:~# kubectl -n oas-apps get hr 
NAME         RELEASE      PHASE              STATUS     MESSAGE                                                               AGE
nextcloud                 ChartFetchFailed              Chart fetch failed for Helm release 'nc' in 'oas-apps'.               84m
rocketchat   rocketchat   Succeeded          deployed   Release was successful for Helm release 'rocketchat' in 'oas-apps'.   84m
wordpress    wordpress    Succeeded          deployed   Release was successful for Helm release 'wordpress' in 'oas-apps'.    84m
root@flux-extra-opts:~# kubectl -n oas-apps describe hr nextcloud
Name:         nextcloud
Namespace:    oas-apps
Labels:       fluxcd.io/sync-gc-mark=sha256.bfXHy-smXt1VRNBuCXxJiThX9hnO429LvxM2En1sgqw
Annotations:  flux.weave.works/automated: false
              fluxcd.io/sync-checksum: 92b96b80d83bbb2465e8487165caefd1865e7b14
API Version:  helm.fluxcd.io/v1
Kind:         HelmRelease
Metadata:
  Creation Timestamp:  2020-06-18T14:31:10Z
  Generation:          1
  Managed Fields:
    API Version:  helm.fluxcd.io/v1
    Fields Type:  FieldsV1
    fieldsV1:
      f:metadata:
        f:annotations:
          .:
          f:flux.weave.works/automated:
          f:fluxcd.io/sync-checksum:
          f:kubectl.kubernetes.io/last-applied-configuration:
        f:labels:
          .:
          f:fluxcd.io/sync-gc-mark:
      f:spec:
        .:
        f:chart:
          .:
          f:git:
          f:path:
          f:ref:
        f:releaseName:
        f:timeout:
        f:valuesFrom:
        f:wait:
    Manager:      kubectl
    Operation:    Update
    Time:         2020-06-18T14:31:10Z
    API Version:  helm.fluxcd.io/v1
    Fields Type:  FieldsV1
    fieldsV1:
      f:spec:
        f:rollback:
        f:values:
      f:status:
        .:
        f:conditions:
        f:observedGeneration:
        f:phase:
    Manager:         helm-operator
    Operation:       Update
    Time:            2020-06-18T15:51:11Z
  Resource Version:  13138
  Self Link:         /apis/helm.fluxcd.io/v1/namespaces/oas-apps/helmreleases/nextcloud
  UID:               eb94e4e8-83e1-4622-b980-908074714bdd
Spec:
  Chart:
    Git:         https://open.greenhost.net/openappstack/nextcloud
    Path:        .
    Ref:         0.2.3
  Release Name:  nc
  Timeout:       1800
  Values From:
    Secret Key Ref:
      Key:   values.yaml
      Name:  nextcloud-settings
  Wait:      true
Status:
  Conditions:
    Last Transition Time:  2020-06-18T14:31:18Z
    Last Update Time:      2020-06-18T15:51:11Z
    Message:               Chart fetch failed for Helm release 'nc' in 'oas-apps'.
    Reason:                ChartFetchFailed
    Status:                False
    Type:                  ChartFetched
    Last Transition Time:  2020-06-18T14:31:18Z
    Last Update Time:      2020-06-18T15:51:11Z
    Message:               Chart fetch failed for Helm release 'nc' in 'oas-apps'.
    Reason:                ChartFetchFailed
    Status:                False
    Type:                  Released
  Observed Generation:     1
  Phase:                   ChartFetchFailed
Events:
  Type     Reason             Age                  From           Message
  ----     ------             ----                 ----           -------
  Warning  FailedReleaseSync  4m17s (x5 over 83m)  helm-operator  synchronization of release 'nc' in namespace 'oas-apps' failed: failed to prepare chart for release: no repository definition for @stable, @stable, @stable, @stable. Please add them via 'helm repo add'