Tests dereference NULL after non-stopping assertions #46

Three tests dereference pointers immediately after assertion macros that record failure but do not stop execution. A failed lookup can therefore turn a useful assertion failure into a process crash.

Acceptance criteria:

• Prevent dereferences after a failed null assertion in test_registry.c, test_game_engine.c, and test_eremote.c.
• Preserve the assertion failure and nonzero test result.
• Keep the change test-only.

Tracked by PR #45.