Save to collections after deleting all the collections causes an error page

[aksappy]

Describe the bug
When trying to save to collection, after deleting all the existing collection throws

this.$store.state.postwoman.collections[this.$data.requestData.collectionIndex] is undefined

To Reproduce
Steps to reproduce the behavior:

1. Save a request to an existing collection.
2. Delete all the existing collections
3. Click on Save to Collections
4. Error is seen, in addition to that neither "Go Home" or "Reload" does not work.

Expected behavior
Either say that there is no collection OR Save without a collection OR prompt for new collection

Screenshots

Desktop (please complete the following information):

• OS: Windows 10
• Browser: Firefox
• 70.0.1

[ialexreis]

I'm checking out this bug, and I detected that some array validation was missing.

Maybe this should be fixed with the recreation of a default collection "My Collection", in background or with a modal showing on the page, with the collection creation form.

What do you guys think is the best solution?

[ialexreis]

@liyasthomas Implemented this validation, to prevent this bug from happenning..
Launching PR.