Report js errors to google analytics

error.js

window.onerror = (msg, file, line, column, error=null)=>{
  
  try{
    if(error){ // error param not supported everywhere
            msg = error.stack; 

    }
    ga('send','event','error', `${file}:{line}`, msg)
  }catch(e){
    // no-op
  }
}