Fix crash in QLottieGradientHolder with no gradient


If the m_gradient is null, we would still dereference it and
crash.

Pick-to: 6.12
Change-Id: I52e0951bc7d1d60f5efe2eabd1c2c2b780dbe31b
Reviewed-by: Kwanghyo Park <kwanghyo.park@qt.io>
commit730f53a38bd88d8485faedf7581dfab73ca0a0d5
parent11215cd8aef205d9aa619e53e96a77096b50a724
authorEskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
committerEskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
commit timeWed, 12 Aug 2026 15:36:44 +0000