Throws exception on my machine for missing swish-min.js

This actually might be the cause of it being slow.


Service	Errors	Success	Min	Q1	Mean	Q3	Max
swi-prolog	0	5	0.580	0.584	0.588	0.730	0.860
search-swi-prolog	0	3	3.050	3.050	3.064	3.110	3.110
swish	0	5	0.370	0.371	0.388	0.412	0.420
swish-min.js	4	4	-	-	-	-	-