ui: fix null reference error in setTheme
ui: fix null reference error in setTheme

skydive-project/skydive,safchain/skydive,safchain/skydive,safchain/skydive,skydive-project/skydive,skydive-project/skydive,skydive-project/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,safchain/skydive,lebauce/skydive,lebauce/skydive,safchain/skydive,lebauce/skydive,skydive-project/skydive,safchain/skydive,lebauce/skydive,safchain/skydive,lebauce/skydive,safchain/skydive,lebauce/skydive