Dracula errors on (just) + or - at REPL

[pnkfelix]

Start Dracula (bug happens in both ACL2 and Modular ACL2)

Go to the REPL. Type + and hit enter.
You can do the same thing for -

I get the following internal error from DrScheme?:

char-ci=?: expects type <character> as 1st argument, given: #<eof>; other arguments were: #\i

 === context ===
/Users/pnkfelix/Library/PLT Scheme/planet/300/4.1.5/cache/cce/dracula.plt/8/2/lang/acl2-readtable.ss:64:6: check-infinity
/Applications/PLT Scheme v4.1.5/collects/scheme/private/contract-arrow.ss:1347:3
/Applications/PLT Scheme v4.1.5/collects/framework/private/text.ss:2071:4: on-local-char method in ...work/private/text.ss:1910:2
/Applications/PLT Scheme v4.1.5/collects/scheme/private/more-scheme.ss:155:2: call-with-break-parameterization
/Applications/PLT Scheme v4.1.5/collects/scheme/private/more-scheme.ss:271:2: call-with-exception-handler

Note that the internal error does not happen if you just do * at the REPL.

I assume the problem here is that there's a makeshift lexer that assumes you're trying to read a token like +inf.0 or -inf.0, and is not prepared for the sudden end to input stream.