File type validation while importing query

test were run on : Chrome 57.0.2987.110 (64-bit)

If by mistake I import a jpeg in Import query in query workbench, it does import and the browser cache runs out of memory because of this mistake.

If we are only allowing to save the query in a .txt file while export , I think it would be good idea if we do a javascript validation for valid filetype while import.