Add error handling, change attribute syntax

[johnparn]

Hi!

Tried pulsar-express out and ran into some minor issues in master. I haven't done any VueJS before so the changes I propose may be solved in a bit more vueish way.

Anyway, I added error handling for dynamic image requiring in breadcrumb as workers.png is missing in assets. There is a change of attribute syntax to use v-bind instead of interpolation of value inside attributes on workers page as the compiler threw an error on that.