WebGL missing fonts

I complied the webgl samples successfully, but when I run it with the vs code live server, the console printed as below.

occt-webgl-sample.js:1001 Font_FontMgr, error: unable to find any font!
occt-webgl-sample.js:1001 TKOpenGl | Type: Error | ID: 0 | Severity: High | Message:
  Font 'Courier' is not found in the system!
occt-webgl-sample.js:1001 Font_FontMgr, error: unable to find any font!
occt-webgl-sample.js:1001 TKOpenGl | Type: Error | ID: 0 | Severity: High | Message:
  Font 'sans-serif' is not found in the system!

Can anyone help me? Thanks for help sincerely.