From 654c569498a5e895ec09b7ec3926bd5f64515550 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sa=C3=BAl=20Ibarra=20Corretg=C3=A9?= <s@saghul.net>
Date: Fri, 22 May 2026 12:05:36 +0200
Subject: [PATCH 1/2] Walk the cause chain when dumping uncaught errors

---
 quickjs-libc.c | 51 ++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 12 deletions(-)

diff --git a/quickjs-libc.c b/quickjs-libc.c
index 56c38453b..8ba8a6dbf 100644
--- a/quickjs-libc.c
+++ b/quickjs-libc.c
@@ -4720,22 +4720,49 @@ static void js_dump_obj(JSContext *ctx, FILE *f, JSValueConst val)
     }
 }
 
+#define JS_DUMP_ERROR_MAX_CAUSE_DEPTH 10
+
 static void js_std_dump_error1(JSContext *ctx, JSValueConst exception_val)
 {
-    JSValue val;
+    JSValue val, current;
     bool is_error;
-
-    is_error = JS_IsError(exception_val);
-    js_dump_obj(ctx, stderr, exception_val);
-    if (is_error) {
-        val = JS_GetPropertyStr(ctx, exception_val, "stack");
-    } else {
-        js_std_cmd(/*ErrorBackTrace*/2, ctx, &val);
-    }
-    if (!JS_IsUndefined(val)) {
-        js_dump_obj(ctx, stderr, val);
-        JS_FreeValue(ctx, val);
+    int depth;
+
+    current = JS_DupValue(ctx, exception_val);
+    for (depth = 0; ; depth++) {
+        is_error = JS_IsError(current);
+        js_dump_obj(ctx, stderr, current);
+        if (is_error) {
+            val = JS_GetPropertyStr(ctx, current, "stack");
+            if (JS_IsException(val)) {
+                JS_FreeValue(ctx, JS_GetException(ctx));
+                val = JS_UNDEFINED;
+            }
+        } else if (depth == 0) {
+            js_std_cmd(/*ErrorBackTrace*/2, ctx, &val);
+        } else {
+            val = JS_UNDEFINED;
+        }
+        if (!JS_IsUndefined(val)) {
+            js_dump_obj(ctx, stderr, val);
+            JS_FreeValue(ctx, val);
+        }
+        if (!is_error || depth >= JS_DUMP_ERROR_MAX_CAUSE_DEPTH)
+            break;
+        val = JS_GetPropertyStr(ctx, current, "cause");
+        if (JS_IsException(val)) {
+            JS_FreeValue(ctx, JS_GetException(ctx));
+            break;
+        }
+        if (JS_IsUndefined(val)) {
+            JS_FreeValue(ctx, val);
+            break;
+        }
+        fputs("Caused by: ", stderr);
+        JS_FreeValue(ctx, current);
+        current = val;
     }
+    JS_FreeValue(ctx, current);
 }
 
 void js_std_dump_error(JSContext *ctx)

From fc3e1ea6738e674f30c07a91db9280cbc26c178f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sa=C3=BAl=20Ibarra=20Corretg=C3=A9?= <s@saghul.net>
Date: Sun, 24 May 2026 22:58:23 +0200
Subject: [PATCH 2/2] fixup!

---
 quickjs-libc.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/quickjs-libc.c b/quickjs-libc.c
index 8ba8a6dbf..6926733e0 100644
--- a/quickjs-libc.c
+++ b/quickjs-libc.c
@@ -4734,10 +4734,6 @@ static void js_std_dump_error1(JSContext *ctx, JSValueConst exception_val)
         js_dump_obj(ctx, stderr, current);
         if (is_error) {
             val = JS_GetPropertyStr(ctx, current, "stack");
-            if (JS_IsException(val)) {
-                JS_FreeValue(ctx, JS_GetException(ctx));
-                val = JS_UNDEFINED;
-            }
         } else if (depth == 0) {
             js_std_cmd(/*ErrorBackTrace*/2, ctx, &val);
         } else {
@@ -4750,10 +4746,6 @@ static void js_std_dump_error1(JSContext *ctx, JSValueConst exception_val)
         if (!is_error || depth >= JS_DUMP_ERROR_MAX_CAUSE_DEPTH)
             break;
         val = JS_GetPropertyStr(ctx, current, "cause");
-        if (JS_IsException(val)) {
-            JS_FreeValue(ctx, JS_GetException(ctx));
-            break;
-        }
         if (JS_IsUndefined(val)) {
             JS_FreeValue(ctx, val);
             break;