Use null-safe operator for character properties access

[herpaderpaldent]

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[what-the-diff]

PR Summary

• Improved Retrieval of 'corporation_id'
  We've upgraded the method we use to fetch the corporation_id from the character details. We're now using a technique that can cleverly prevent potential mistakes if the character details aren't available.

• Enhanced Safety for 'alliance_id' Retrieval
  Just like we did above, we've also revised the method for fetching the alliance_id from character details. This modification boosts our code's defences, dramatically reducing the risk of troubles arising.