Error line numbers off-by-1 for <script> tags

Thanks for the awesome work on Blockbuilder! I'm loving the error notification, but it seems to be off by one if the error occurs inside a `` tag. For example, in the below screenshot, the error should be on the line that imports `d3.geo.tile.min.js`.


Here's an [example you can use to reproduce the issue](http://blockbuilder.org/curran/5a415caef559cb84acb542f3af39e51e).

When I first encountered the error, my screen looked like this:


and I spent some time barking up the wrong tree, thinking the error was from the topojson script.

All the best!