fix: 修复 style 为空的报错问题

[heiyexing]

PR includes

• [x] 修复 style 为空报错的问题

[github-actions[bot]]

🎊 PR Preview e7818e6e6fc5f99b14166e07b2d8d840daa78f58 has been successfully built and deployed to https://antvis-L7Draw-preview-pr-139.surge.sh

:clock1: Build time: 157.613s

_{🤖 By surge-preview}