Prelude.(!!): index too large

[deefactorial]

I get this error when running this program on one font file.

here is the font file: http://fontsov.com/font/scalasansregular8008.html

./webify-linux-x86_64 ScalaSans.ttf 
Generating ScalaSans.eot
Generating ScalaSans.woff
Generating ScalaSans.svg
Available cmaps
-------------------------------------------------------
PlatformId | EncodingId | Description                  
0          | 0          | Unicode 1.0 semantics        
1          | 0          | Macintosh Roman 8-bit simple 
3          | 1          | Microsoft Unicode BMP (UCS-2)
-------------------------------------------------------
Selecting platformId 3 encodingId 1 -- Microsoft Unicode BMP (UCS-2)
Failed to convert ScalaSans.ttf
Prelude.(!!): index too large