Description of problem:
When we create a migration storage using a secret that is not placed inside openshift-config namespace and we delete it, the UI crashes.


Version-Release number of selected component (if applicable):
MTC 1.6.0
SOURCE CLUSTER: AWS 4.8 MTC 1.6.0
TARGET CLUSTER: AWS 4.9 MTC 1.6.0

How reproducible:
Always

Steps to Reproduce:
1. Remove all migration storage resources

2. Create this minio migration storage

SECRET

$ cat <<EOF | oc create -f -
apiVersion: v1
data:
  aws-access-key-id: ZmFrZXNlY3JldA==
  aws-secret-access-key: ZmFrZXNlY3JldA==
kind: Secret
metadata:
  name: aws.automation.test-creds
  namespace: openshift-migration
type: Opaque
EOF


MIGSTORAGE

$ cat <<EOF | oc create -f -
apiVersion: migration.openshift.io/v1alpha1
kind: MigStorage
metadata:
  name: aws.automation.test
  namespace: openshift-migration
spec:
  backupStorageConfig:
    awsBucketName: miniobucket
    awsS3Url: http://minio-minio.apps.cam-xxx-xxx.yy.xxx.xxx.com
    credsSecretRef:
      name: aws.automation.test-creds
      namespace: openshift-migration
    insecure: true
  backupStorageProvider: aws
  volumeSnapshotConfig:
    credsSecretRef:
      name: aws.automation.test-creds
      namespace: openshift-migration
  volumeSnapshotProvider: aws
EOF



3. Go to the UI and delete the migration storage created in step 2


Actual results:
The UI crashes and in the browser's console we can read this error

app.bundle.js:2 Error: Minified React error #31; visit https://reactjs.org/docs/error-decoder.html?invariant=31&args[]=object%20with%20keys%20%7Bmessage%2C%20name%2C%20stack%2C%20config%7D for the full message or use the non-minified dev environment for full errors and additional helpful warnings.

app.bundle.js:2 Uncaught (in promise) Error: Minified React error #31; visit https://reactjs.org/docs/error-decoder.html?invariant=31&args[]=object%20with%20keys%20%7Bmessage%2C%20name%2C%20stack%2C%20config%7D for the full message or use the non-minified dev environment for full errors and additional helpful warnings.


Expected results:
The UI should not crash

Additional info:
In order to make the UI work again we can go to (in a chrome browser)

right click -> inspect -> Application -> Storage -> Local Storage  -> 

And remove the keys "persist:root" and "currentUser"

After removing those keys refresh the UI and it will start working again without problems.