POLIO-1810: make check on grouped campaigns null safe

[quang-le]

What problem is this PR solving? Explain here in one sentence.

Related JIRA tickets : POLIO-1810

Self proofreading checklist

• Did I use eslint and black formatters
• Is my code clear enough and well documented
• Are my typescript files well typed
• New translations have been added or updated if new strings have been introduced in the frontend
• My migrations file are included
• Are there enough tests
• Documentation has been included (for new feature)

Doc

Tell us where the doc can be found (docs folder, wiki, in the code...).

Changes

make check on grouped campaigns null safe in Dashboard.tsx

How to test

This is an edge case that I couldn't reproduce "naturally" so:

• mock an API response from the campaigns API where a campaign doesn't have the grouped_campaigns key value

Print screen / video

NA

See Jira ticket for mink to initial sentry error

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fix: empty instance pop up

Refs: IA-3665

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