Error running the Roll a Ball demo on WebGL

Ok so I'm a complete beginner using Unity. Today I built my first game from the Roll a Ball demo. Lots of fun a it works great on when I build for my mac. However.... when I build for web I get this error even when I try running my program from localhost.

An error occured running the Unity content on this page. See your browser JavaScript console for more info. The error was: abort(108) at jsStackTrace (Roll a Ball (Web).asm.framework.unityweb:2:27474) stackTrace (Roll a Ball (Web).asm.framework.unityweb:2:27648) abort (Roll a Ball (Web).asm.framework.unityweb:4:30901) Zgl (Roll a Ball (Web).asm.code.unityweb:22:103018) fLk (Roll a Ball (Web).asm.code.unityweb:17:625258) eLk (Roll a Ball (Web).asm.code.unityweb:17:624784) K6i (Roll a Ball (Web).asm.code.unityweb:4:449410) dbl (Roll a Ball (Web).asm.code.unityweb:22:79439) invoke_iiii (Roll a Ball (Web).asm.framework.unityweb:2:348349) Iuk (Roll a Ball (Web).asm.code.unityweb:17:426865) Qxk (Roll a Ball (Web).asm.code.unityweb:17:456005) tZ (Roll a Ball (Web).asm.code.unityweb:7:330108) rZ (Roll a Ball (Web).asm.code.unityweb:7:329005) TSa (Roll a Ball (Web).asm.code.unityweb:13:264468) SSa (Roll a Ball (Web).asm.code.unityweb:13:263197) OCb (Roll a Ball (Web).asm.code.unityweb:8:298253) hnb (Roll a Ball (Web).asm.code.unityweb:10:640371) iNa (Roll a Ball (Web).asm.code.unityweb:12:1046496) W9 (Roll a Ball (Web).asm.code.unityweb:7:808123) J9 (Roll a Ball (Web).asm.code.unityweb:7:797622) Jal (Roll a Ball (Web).asm.code.unityweb:22:76759) browserIterationFunc (Roll a Ball (Web).asm.framework.unityweb:2:47998) runIter (Roll a Ball (Web).asm.framework.unityweb:2:51075) Browser_mainLoop_runner (Roll a Ball (Web).asm.framework.unityweb:2:49540) If this abort() is unexpected, build with -s ASSERTIONS=1 which can give more information.

Any ideas?