js-on-sx: object literal __proto__ + try/catch error wrapping

lib/js/runtime.sx

@@ -991,6 +991,34 @@
 
 (define SuppressedError :js-undefined)
 
+(define
+  js-str-startswith?
+  (fn
+    (s prefix)
+    (cond
+      ((< (len s) (len prefix)) false)
+      (else (= (js-string-slice s 0 (len prefix)) prefix)))))
+
+(define
+  js-wrap-exn
+  (fn
+    (e)
+    (cond
+      ((not (= (type-of e) "string")) e)
+      ((js-str-startswith? e "Undefined symbol:")
+        (js-new-call ReferenceError (js-args e)))
+      ((js-str-startswith? e "TypeError:")
+        (js-new-call TypeError (js-args (js-string-slice e 11 (len e)))))
+      ((js-str-startswith? e "RangeError:")
+        (js-new-call RangeError (js-args (js-string-slice e 12 (len e)))))
+      ((js-str-startswith? e "SyntaxError:")
+        (js-new-call SyntaxError (js-args (js-string-slice e 13 (len e)))))
+      ((js-str-startswith? e "ReferenceError:")
+        (js-new-call ReferenceError (js-args (js-string-slice e 16 (len e)))))
+      ((js-str-startswith? e "URIError:")
+        (js-new-call URIError (js-args (js-string-slice e 10 (len e)))))
+      (else e))))
+
 (define
   js-date-from-one
   (fn
@@ -3194,7 +3222,12 @@
 
 (define
   js-make-obj
-  (fn () (let ((d (dict))) (begin (dict-set! d "__js_order__" (list)) d))))
+  (fn ()
+    (let ((d (dict)))
+      (begin
+        (dict-set! d "__js_order__" (list))
+        (dict-set! d "__proto__" (get Object "prototype"))
+        d))))
 
 (define
   js-obj-order-add!