Log code snippet next to syntax errors

[mbostock]

When the preview server encounters a syntax error, it logs the message to the console:

SyntaxError: Assignment to external variable 'x' at line 4, column 1

It would be nicer if this message included the file with the syntax error, and a snippet of code to point to the error in context.

[mootari]

Does this issue depend on #7 ?

[borango]

it would help me already if I had a sourcefile where I can lookup 'line 4, column 1'.

The line number does not relate to my .md source file. It rather seems to be relative to a fenced code block. So the line number relative to my .md source would be most helpful.