js-on-sx: new <non-callable> throws TypeError instead of hanging

new (new Object("")) hung because js-new-call called
js-get-ctor-proto -> js-ctor-id -> inspect, and inspect on a
wrapper-with-proto-chain recurses through the prototype's
lambdas forever. Added (js-function? ctor) precheck at the top
of js-new-call that raises a TypeError instance instead.
conformance.sh: 148/148.

lib/js/runtime.sx

@@ -683,18 +683,22 @@
   js-new-call
   (fn
     (ctor args)
-    (let
-      ((obj (dict)))
-      (begin
-        (dict-set! obj "__proto__" (js-get-ctor-proto ctor))
+    (cond
+      ((not (js-function? ctor))
+        (raise (js-new-call TypeError (list (str (type-of ctor) " is not a constructor")))))
+      (else
         (let
-          ((ret (js-call-with-this obj ctor args)))
-          (if
-            (and
-              (not (js-undefined? ret))
-              (or (= (type-of ret) "dict") (= (type-of ret) "list") (js-function? ret)))
-            ret
-            obj))))))
+          ((obj (dict)))
+          (begin
+            (dict-set! obj "__proto__" (js-get-ctor-proto ctor))
+            (let
+              ((ret (js-call-with-this obj ctor args)))
+              (if
+                (and
+                  (not (js-undefined? ret))
+                  (or (= (type-of ret) "dict") (= (type-of ret) "list") (js-function? ret)))
+                ret
+                obj))))))))
 
 ;; Setter — mutates the dict. Returns the new value (JS assignment yields rhs).
 (define

lib/js/test262-scoreboard.json

@@ -1,37 +1,37 @@
 {
   "totals": {
-    "pass": 80,
-    "fail": 13,
-    "skip": 1,
-    "timeout": 6,
-    "total": 100,
-    "runnable": 99,
-    "pass_rate": 80.8
+    "pass": 23,
+    "fail": 20,
+    "skip": 5,
+    "timeout": 2,
+    "total": 50,
+    "runnable": 45,
+    "pass_rate": 51.1
   },
   "categories": [
     {
-      "category": "built-ins/String",
-      "total": 100,
-      "pass": 80,
-      "fail": 13,
-      "skip": 1,
-      "timeout": 6,
-      "pass_rate": 80.8,
+      "category": "built-ins/Array",
+      "total": 50,
+      "pass": 23,
+      "fail": 20,
+      "skip": 5,
+      "timeout": 2,
+      "pass_rate": 51.1,
       "top_failures": [
         [
           "Test262Error (assertion failed)",
-          11
+          17
+        ],
+        [
+          "TypeError: not a function",
+          2
         ],
         [
           "Timeout",
-          6
+          2
         ],
         [
-          "ReferenceError (undefined symbol)",
-          1
-        ],
-        [
-          "SyntaxError (parse/unsupported syntax)",
+          "Unhandled: Not callable: {:2 43 :1 42 :0 41 :length 3}\\",
           1
         ]
       ]
@@ -40,22 +40,22 @@
   "top_failure_modes": [
     [
       "Test262Error (assertion failed)",
-      11
+      17
+    ],
+    [
+      "TypeError: not a function",
+      2
     ],
     [
       "Timeout",
-      6
+      2
     ],
     [
-      "ReferenceError (undefined symbol)",
-      1
-    ],
-    [
-      "SyntaxError (parse/unsupported syntax)",
+      "Unhandled: Not callable: {:2 43 :1 42 :0 41 :length 3}\\",
       1
     ]
   ],
   "pinned_commit": "d5e73fc8d2c663554fb72e2380a8c2bc1a318a33",
-  "elapsed_seconds": 154.6,
+  "elapsed_seconds": 160.3,
   "workers": 1
 }

lib/js/test262-scoreboard.md

@@ -1,28 +1,28 @@
 # test262 scoreboard
 
 Pinned commit: `d5e73fc8d2c663554fb72e2380a8c2bc1a318a33`
-Wall time: 154.6s
+Wall time: 160.3s
 
-**Total:** 80/99 runnable passed (80.8%). Raw: pass=80 fail=13 skip=1 timeout=6 total=100.
+**Total:** 23/45 runnable passed (51.1%). Raw: pass=23 fail=20 skip=5 timeout=2 total=50.
 
 ## Top failure modes
 
-- **11x** Test262Error (assertion failed)
-- **6x** Timeout
-- **1x** ReferenceError (undefined symbol)
-- **1x** SyntaxError (parse/unsupported syntax)
+- **17x** Test262Error (assertion failed)
+- **2x** TypeError: not a function
+- **2x** Timeout
+- **1x** Unhandled: Not callable: {:2 43 :1 42 :0 41 :length 3}\
 
 ## Categories (worst pass-rate first, min 10 runnable)
 
 | Category | Pass | Fail | Skip | Timeout | Total | Pass % |
 |---|---:|---:|---:|---:|---:|---:|
-| built-ins/String | 80 | 13 | 1 | 6 | 100 | 80.8% |
+| built-ins/Array | 23 | 20 | 5 | 2 | 50 | 51.1% |
 
 ## Per-category top failures (min 10 runnable, worst first)
 
-### built-ins/String  (80/99 — 80.8%)
+### built-ins/Array  (23/45 — 51.1%)
 
-- **11x** Test262Error (assertion failed)
-- **6x** Timeout
-- **1x** ReferenceError (undefined symbol)
-- **1x** SyntaxError (parse/unsupported syntax)
+- **17x** Test262Error (assertion failed)
+- **2x** TypeError: not a function
+- **2x** Timeout
+- **1x** Unhandled: Not callable: {:2 43 :1 42 :0 41 :length 3}\

plans/js-on-sx.md

@@ -158,6 +158,8 @@ Each item: implement → tests → update progress. Mark `[x]` when tests green.
 
 Append-only record of completed iterations. Loop writes one line per iteration: date, what was done, test count delta.
 
+- 2026-05-08 — **`new <non-callable>` throws TypeError instead of hanging.** `new (new Object(""))` (calling `new` on a String wrapper dict) hung because `js-new-call` called `js-get-ctor-proto` which fell through to `js-ctor-id` which called `inspect ctor` — and `inspect` on a wrapper-with-proto-chain recurses through the prototype's lambdas forever. Added a `(js-function? ctor)` precheck at the top of `js-new-call`: when the receiver isn't callable, raise a `TypeError` instance instead. Now `try { new x } catch(e) { e instanceof TypeError }` returns `true` for non-callable `x`. conformance.sh: 148/148. String 80/99, Array 23/45 maintained.
+
 - 2026-05-08 — **JS functions accept extra args silently (per spec).** SX strictly arity-checks: `(fn (a) ...)` rejects 2 args, but JS allows passing more args than declared (the extras are accessible via `arguments`). Was raising `f expects 1 args, got 2` whenever Array.from passed `(value, index)` to a 1-arg mapFn, etc. Fixed in `js-build-param-list` (transpile.sx): every JS function param list now ends with `&rest __extra_args__` (unless an explicit rest param is already present), so extras are silently absorbed. Headline scoreboards unchanged but unblocks a class of harness-mediated failures. conformance.sh: 148/148.
 
 - 2026-05-08 — **Lowered array padding bail-out from 2^32-1 to 1M.** Yesterday's 2^32-1 threshold still allowed indices like `2147483648` to pad billions of `js-undefined` entries, hanging the worker. Without sparse-array support there's no semantic value in supporting >1M sparse padding; lowering the bail to 1M turns those tests into fast assertion failures instead of timeouts. Removes another timeout (Array 7→1). built-ins/Array stays at 23/45, but the run is faster and no longer wall-time-bound. conformance.sh: 148/148.