don't forget this case

beautiful-racket-demo/jsonic-demo-2/indenter.rkt

@@ -8,6 +8,9 @@
 (define (indent-jsonic tbox [posn 0])
   (define prev-line (previous-line tbox posn))
   (define current-line (line tbox posn))
+  (cond
+    [(not prev-line) 0]
+    [else
      (define prev-indent (line-indent tbox prev-line))
      (cond
        [(left-bracket?
@@ -16,7 +19,7 @@
        [(right-bracket?
          (line-first-visible-char tbox current-line))
         (- prev-indent indent-width)]
-    [else prev-indent]))
+       [else prev-indent])]))
 (provide
  (contract-out
   [indent-jsonic (((is-a?/c text%)) 
@@ -28,7 +31,7 @@
   (define test-str #<<HERE
 #lang jsonic
 {
-"value",
+"value": 42,
 "string":
 [
 {

beautiful-racket-demo/jsonic-demo-3/indenter.rkt

@@ -8,6 +8,9 @@
 (define (indent-jsonic tbox [posn 0])
   (define prev-line (previous-line tbox posn))
   (define current-line (line tbox posn))
+  (cond
+    [(not prev-line) 0]
+    [else
      (define prev-indent (line-indent tbox prev-line))
      (cond
        [(left-bracket?
@@ -16,7 +19,7 @@
        [(right-bracket?
          (line-first-visible-char tbox current-line))
         (- prev-indent indent-width)]
-    [else prev-indent]))
+       [else prev-indent])]))
 (provide
  (contract-out
   [indent-jsonic (((is-a?/c text%)) 
@@ -28,7 +31,7 @@
   (define test-str #<<HERE
 #lang jsonic
 {
-"value",
+"value": 42,
 "string":
 [
 {