Description of problem:
When we cancel a migration and execute it again, the UI shows a blank screen. If we refresh the browser, everything is shown properly again.

Version-Release number of selected component (if applicable):
CMT 1.3
SOURCE CLUSTER: azure 4.2
TARGET CLUSTER: azure 4.5
Browser: Chrome

How reproducible:
Always

Steps to Reproduce:
1. Deploy an application

$ oc process -p NAMESPACE=nginx-example -f https://github.com/sergiordlr/temp-testfiles/blob/master/app_migration/nginx_pvs/nginx_with_pv_defaultsc_template.yml?raw=true | oc create -f -

2. Create a migration plan for the application

3. Execute the migration plan. Quiesced migration.

4. Wait until pods are quiesced in the source cluster and cancel the migration.

5. Execute the migration again


Actual results:
After we click on "Migrate" in step 5, the screen becomes blank. And an error is shown in the browser's console:


app.bundle.js:106 TypeError: Cannot read property 'some' of null
    at app.bundle.js:58
    at Array.filter (<anonymous>)
    at app.bundle.js:58
    at Array.map (<anonymous>)
    at app.bundle.js:58
    at app.bundle.js:50
    at app.bundle.js:50
    at app.bundle.js:50
    at app.bundle.js:50
    at app.bundle.js:50

Expected results:
The UI should show the screen normally, with the new migration execution running.

Additional info:

If we refresh the browser with F5, the UI starts working fine again.