passing non-block to #do: freezes slate

[Timmy Douglas]

running:

#(1 2 3) do: {| :blah | blah }.

doesn't seem to return. It should probably throw an error instead.

(It'd be nice if repl noviceMode would be false by default, or at
least the default behavior would drop the user into the debugger
instead of skipping over errors.)

It also seems like if i paste a lot of loads into the repl, it will
keep loading new files after it hits an error even when noviceMode is
false.