Applying an invalid Group Code at checkout triggers a fatal error

[dwanjuki]

Describe the bug
Applying an invalid Group Code at checkout triggers a fatal error: Uncaught Error: Call to a member function can_claim_level() on null

To Reproduce
Steps to reproduce the behavior:

1. Create a child group level.
2. Go to child level checkout.
3. Enter a code that doesn't exist e.g., abcde, and click Apply Code
4. See error

Isolating the problem (mark completed items with an [x]):

• I have deactivated other plugins and confirmed this bug occurs when only Paid Memberships Pro plugin is active.
• This bug happens with a default WordPress theme active, or Memberlite.
• I can reproduce this bug consistently using the steps above.

WordPress Environment

WP 6.5.2 PMPro 3.0.3 PMPro Group Accounts 1.0.1