fix duk_def_prop_index() (key and value were swapped), fix tracedata length

src/duk_api_object.c

@@ -243,6 +243,7 @@ void duk_def_prop_index(duk_context *ctx, int obj_index, unsigned int arr_index,
 	 */
 	obj_index = duk_require_normalize_index(ctx, obj_index);
 	duk_push_number(ctx, (double) arr_index);  /* FIXME: push u32 */
+	duk_insert(ctx, -2);  /* [ key value ] */
 	duk_def_prop(ctx, obj_index, desc_flags);
 }
 

src/duk_error_augment.c

@@ -120,6 +120,10 @@ static void add_traceback(duk_hthread *thr, duk_hthread *thr_callstack, duk_hobj
 		arr_idx++;
 	}
 
+	/* FIXME: set with duk_hobject_set_length() when tracedata is filled directly */
+	duk_push_int(ctx, (int) arr_idx);
+	duk_def_prop_stridx(ctx, -2, DUK_STRIDX_LENGTH, DUK_PROPDESC_FLAGS_WC);
+
 	/* [... arr] */
 	duk_def_prop_stridx(ctx, err_index, DUK_STRIDX_TRACEDATA, DUK_PROPDESC_FLAGS_WEC);  /* -> [...] */
 }