G30 » Exercises G30

Failing to add diamonds from completed challenges to the total count after reaching level 15.

Steps to reproduce:
1. Make progress to level 15 in the game.
2. Complete a challenge and receive the diamond reward.
3. Check the total diamond count before and after completing the challenge.
4. Take a note that the diamonds earned from completing challenges at level 15 are not added to the total count.

Expected result:
Diamonds earned from completing challenges at level 15 should be added to the total diamond count, reflecting the player's progress accurately.

Actual result:
Diamonds earned from completing challenges at level 15 are not added to the total count, leading to an inaccurate representation of the player's total diamond count.