TypeError: Cannot read property 'type' of undefined

rlet.js

/*** CONTROL CONSTUCTS ***/

/* rif expr expr1 expr2
   equivalent to (expr ? expr1 : expr2)  
   Note: The Javascript if is a "statement-if", so this is the "expression-if" */

macro rif {
  case {_ ($e:expr, $e1:expr, $e2:expr)}
    => {return #{(($e) ? ($e1) : ($e2))}}}


/* cond [expr body] ...
   cond [expr body] ... [else default]
   Racket cond, except body here is a single expression */

macro cond {
  case { _ [$e:expr => $result:expr] $more ... }
    => { return #{ rif($e, $result, (cond $more ...))}}
  case { _ [$e:expr    $result:expr] $more ... }
    => { return #{ rif($e, $result, (cond $more ...))}}
  case { _ [$[else] $e:expr]}
    => {return #{$e}} 
  case { _ }    
    => {return #{ void(0) }} }


/*** BINDING CONSTRUCTS ***/

/* rlet (id=expr, ...) body
   Racket let binding 
   Evaluate the expressions, bind the results to the identifiers id... in body.
   The scope of the identifiers does not include the expressions.
*/   

macro rlet {
  case { _ ( ) {$body:expr}}
    => { return #{ (function () {return $body} )()} }  
  case { _ ( $($id:ident = $val:expr) (,) ... ) {$e:expr (;) ... $body:expr} }
    => { return #{(function ($id (,) ...) {$e (;) ... ; return $body})($val (,) ...)} } 
  case { _ ( ) $body}
    => { return #{ (function () $body )()} }
  case { _ ( $($id:ident = $val:expr) (,) ... ) $body }
    => { return #{(function ($id (,) ...) $body)($val (,) ...)} } }

/* rlets (id=expr, ...) body
   Racket let* binding.
   Evaluate the first expression and bind it to the first identifier.
   Evaluate the second expression and bind it to the second identifier. Etc.
   The scope of an identifier includes the following expressions and the body.
                       rlets (id=expr, ...) {body ...}
   is equivalent to    rlet  (id=0, ...) { id=expr; ... ; body ...}
*/   

macro rlets {
  case { _ () {$body:expr} }
    => { return #{ rlet (){$body} } }
  case { _ ( $($id:ident = $val:expr) (,) ... ) {$e:expr (;)... $body:expr}  }
    => { return #{ rlet ($($id=0)(,)...) {$($id=$val) (;) ... ; $e (;) ... $body } } }
  case { _ ( ) $body}
    => { return #{ (function () $body )()} }
  case { _ ( $($id:ident = $val:expr) (,) ... ) {$body ...} }                   /* HERE */
    => { return #{ rlet ($($id=0)(,)...) {$($id=$val) (;) ... ; $body ...} } }
}


/*** TESTS ***/

function displayln(x) { console.log(x); }

                                   displayln("--- cond tests ---")
/* displayln( cond ); */
displayln( cond [43 "ok"] );
var x=1; displayln( cond [x===1  "ok"] [x===2  "2"]  [x===3  "3"] ); 
var x=2; displayln( cond [x===1  1]    [x===2  "ok"] [x===3  "3"] ); 
var x=3; displayln( cond [x===1  1]    [x===2  "2"]  [else   "ok"] ); 

displayln("--- when and unless ---");
when( 2>3 ) displayln("fail");
when( 2<3 ) { "mumble"; displayln("ok")}
unless (1===2) { displayln("ok"); }
unless (1===1) { displayln("fail"); }

displayln("--- rif ---");
var x=1; 
displayln( rif(x==1,"ok","fail"));
displayln( rif(x==2,"fail","ok") );

displayln("--- rlet ---");
rlet( a=1, b=2) { displayln(rif(a+b==3,"ok","fail")) };
displayln( rif( (rlet(){var y=43; return y})==43,"ok","fail" ));
displayln( rif( (rlet(a=1){ return a;})==1, "ok", "fail"));
displayln( cond [(rlet(a=1,b=2){a+b})==3 "ok"] [else "fail"] );
displayln( cond [(rlet(a=1,b=2){return a+b})==3 "ok"] [else "fail"] );
displayln( cond [(rlet(a=1,b=2){42;        a+b})==3 "ok"] [else "fail"] );  /* this fails bc return */
displayln( cond [(rlet(a=1,b=2){42; return a+b})==3 "ok"] [else "fail"] );

displayln( "--- rlets ---");
displayln( rlets(){"ok"} ); 
displayln( rlets(a=7,b=a+1){rif(a+b==15,"ok","fail")} ); 
displayln( rlets(){var x=2 ; return "ok"} ); 
displayln( rlets(a=7,b=a+1){var x=3; return rif(a+b==18,"ok","fail")} );       /* EXAMPLE */

---------------------
The expander gives this error:

soegaard$ sjs -c -o rlet.js rlet.sjs && less rlet.js

/usr/local/lib/node_modules/sweet.js/lib/sweet.js:101
                    throw err;
                          ^
TypeError: Cannot read property 'type' of undefined
    at takeLine (/usr/local/lib/node_modules/sweet.js/lib/patterns.js:73:21)
    at /usr/local/lib/node_modules/sweet.js/lib/patterns.js:67:20
    at Array.map (native)
    at Function._.map._.collect (/usr/local/lib/node_modules/sweet.js/node_modules/underscore/underscore.js:95:56)
    at takeLineContext (/usr/local/lib/node_modules/sweet.js/lib/patterns.js:66:18)
    at takeLine (/usr/local/lib/node_modules/sweet.js/lib/patterns.js:102:28)
    at /usr/local/lib/node_modules/sweet.js/lib/patterns.js:67:20
    at Array.map (native)
    at Function._.map._.collect (/usr/local/lib/node_modules/sweet.js/node_modules/underscore/underscore.js:95:56)
    at takeLineContext (/usr/local/lib/node_modules/sweet.js/lib/patterns.js:66:18)