REPL breaks on some errors #733
Description
Some errors break a REPL session in such way that it can't be used anymore, arrow keys for browsing history break etc.
This is on 1.4 from npm
$ lsc -d
LiveScript 1.4.0 - use 'lsc --help' for more information
ls> map 1, null
/usr/local/lib/node_modules/livescript/node_modules/prelude-ls/lib/List.js:13
for (i$ = 0, len$ = xs.length; i$ < len$; ++i$) {
^
[TypeError: Cannot read property 'length' of null]
ls>
...
undefined
ls> ^[[A^[[A^[[A^[[A^[[A