测速成功但无法导出图片

[code871]

系统版本：Centos7 64
使用测速版本：stairspeedtest_reborn_v0.5.0_linux64.tar.gz
测速完成的终端输出：
Result: DL.Speed: 5.76MB Max.Speed: 11.75MB UL.Speed: N/A Pk.Loss: 0.00% Avg.Ping: 97.67 Google Ping: 0.00
Now exporting picture...
Segmentation fault

日志：
[2019/12/04 Wed 21:25:26.228020][FILEDL]Test completed. Terminate all threads.
[2019/12/04 Wed 21:25:26.233122][FILEDL]Downloaded 61028096 bytes in 10108 milliseconds.
[2019/12/04 Wed 21:25:26.359943][FILEDL]Multi-thread download test completed.
[2019/12/04 Wed 21:25:26.360063][RAW]0 0 0 32768 259344 821088 1653808 2736576 3761952 6092740 8380114 9822232 11631638 9803948 11532380 11922618 10516054 8452228 14032928 10603776
[2019/12/04 Wed 21:25:26.360185][INFO]Average speed: 5.76MB Max speed: 11.75MB Upload speed: N/A Traffic used in bytes: 61028096
[2019/12/04 Wed 21:25:26.360251][INFO]Killing shadowsocksr-libev...
[2019/12/04 Wed 21:25:26.369034][INFO]All nodes tested. Total/Online nodes: 23/22 Traffic used: 505.99MB
[2019/12/04 Wed 21:25:26.371324][INFO]Now exporting result...
[2019/12/04 Wed 21:25:26.373485][RENDER]Start calculating basic string widths for font 'tools//misc//WenQuanYiMicroHei-01.ttf' at size 12.
[2019/12/04 Wed 21:25:26.374626][RENDER]Calculated basic string widths: Number=9 N/A=28 KB=21 MB=26 GB=23 Percent=14 Dot=5