Errors with valid ES6 import syntax

This results in an error:

module.js

export syntax hi = function(ctx) {
    return #`console.log('hello, world!')`;
}

file2.js

export const TEST = 3;

file.js

import { hi } from "./module.js";
import * as Test from "./file2.js";
hi;

Running sjs file.js results in

/usr/local/lib/node_modules/@sweet-js/cli/node_modules/shift-codegen/dist/token_stream.js:95
      var rightChar = tokenStr.charAt(0);
                               ^

TypeError: tokenStr.charAt is not a function
    at TokenStream.put (/usr/local/lib/node_modules/@sweet-js/cli/node_modules/shift-codegen/dist/token_stream.js:95:32)
    at Token.emit (/usr/local/lib/node_modules/@sweet-js/cli/node_modules/shift-codegen/dist/coderep.js:247:10)
    at /usr/local/lib/node_modules/@sweet-js/cli/node_modules/shift-codegen/dist/coderep.js:444:19
    at Array.forEach (native)
    at Seq.emit (/usr/local/lib/node_modules/@sweet-js/cli/node_modules/shift-codegen/dist/coderep.js:443:21)
    at /usr/local/lib/node_modules/@sweet-js/cli/node_modules/shift-codegen/dist/coderep.js:444:19
    at Array.forEach (native)
    at Seq.emit (/usr/local/lib/node_modules/@sweet-js/cli/node_modules/shift-codegen/dist/coderep.js:443:21)
    at codeGen (/usr/local/lib/node_modules/@sweet-js/cli/node_modules/shift-codegen/dist/index.js:153:7)
    at codegen (/usr/local/lib/node_modules/@sweet-js/cli/node_modules/@sweet-js/core/dist/codegen.js:16:38)