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fetch: report early rejections as unhandled rejections #37434

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0071478
fetch: report early rejections as unhandled rejections
robobun Aug 11, 2026
5a48030
test: assert the missing-file fetch rejection with .rejects
robobun Aug 11, 2026
b2f5d46
test: handling an early fetch rejection must not emit rejectionHandled
robobun Aug 11, 2026
3643b50
test: let the rejection tracker drain before the final forced GC
robobun Aug 11, 2026
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141 changes: 34 additions & 107 deletions src/runtime/webcore/fetch.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -190,10 +190,7 @@ fn data_url_response(data_url_: DataURL, global_this: &JSGlobalObject) -> JSValu
Err(_) => {
let err =
global_this.create_error_instance(format_args!("failed to fetch the data URL"));
return JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
);
return JSPromise::rejected_promise(global_this, err).to_js();
}
};
let blob = Blob::init(data, global_this);
Expand Down Expand Up @@ -365,7 +362,7 @@ fn reject_on_exception(
}
},
};
Ok(JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(global_this, err))
Ok(JSPromise::rejected_promise(global_this, err).to_js())
}

// ──────────────────────────────────────────────────────────────────────────
Expand Down Expand Up @@ -403,12 +400,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
jsc::ErrorCode::MISSING_ARGS,
format_args!("{FETCH_ERROR_NO_ARGS}"),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}

let mut headers: Option<Headers> = None;
Expand Down Expand Up @@ -559,12 +551,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
jsc::ErrorCode::INVALID_URL,
format_args!("{FETCH_ERROR_BLANK_URL}"),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}

if url_str.has_prefix_comptime(b"data:") {
Expand All @@ -575,12 +562,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
Ok(d) => d,
Err(_) => {
let err = ctx.create_error_instance(format_args!("failed to fetch the data URL"));
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}
};
let mut data_url = data_url;
Expand All @@ -600,12 +582,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
jsc::ErrorCode::INVALID_URL,
format_args!("fetch() URL is invalid"),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}
};
let mut url_proxy_buffer = owned_url.into_href().into_vec();
Expand Down Expand Up @@ -1019,11 +996,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
jsc::ErrorCode::INVALID_ARG_VALUE,
format_args!("fetch() proxy URL is invalid"),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this, err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}
let mut buffer: Vec<u8> = Vec::with_capacity(url_proxy_buffer.len());
buffer.extend_from_slice(&url_proxy_buffer);
Expand Down Expand Up @@ -1059,9 +1032,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
format_args!("fetch() proxy URL is invalid"),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this, err,
),
JSPromise::rejected_promise(global_this, err).to_js()
);
}
let mut buffer: Vec<u8> =
Expand Down Expand Up @@ -1143,12 +1114,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
jsc::ErrorCode::INVALID_ARG_TYPE,
format_args!("signal is not of type AbortSignal."),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}

if global_this.has_exception() {
Expand Down Expand Up @@ -1177,12 +1143,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
jsc::ErrorCode::INVALID_ARG_TYPE,
format_args!("signal is not of type AbortSignal."),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}
}

Expand Down Expand Up @@ -1414,12 +1375,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
jsc::ErrorCode::INVALID_ARG_VALUE,
format_args!("{FETCH_ERROR_PROXY_UNIX}"),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}

if global_this.has_exception() {
Expand Down Expand Up @@ -1477,12 +1433,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
bstr::BStr::new(url_path_decoded)
),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}
}

Expand Down Expand Up @@ -1593,12 +1544,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
jsc::ErrorCode::INVALID_ARG_VALUE,
format_args!("protocol must be http:, https: or s3:"),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}
}

Expand All @@ -1610,12 +1556,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
jsc::ErrorCode::INVALID_ARG_VALUE,
format_args!("{FETCH_ERROR_UNEXPECTED_BODY}"),
);
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err,
),
);
return Ok(JSPromise::rejected_promise(global_this, err).to_js());
}

// Fetch spec step 11: reject synchronously for a pre-aborted signal. Runs
Expand All @@ -1631,12 +1572,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
}
}
body.detach();
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
reason,
),
);
return Ok(JSPromise::rejected_promise(global_this, reason).to_js());
}
}

Expand Down Expand Up @@ -1674,11 +1610,11 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
old.detach();
break 'prepare_body;
}
let rejected_value =
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
global_this.create_error_instance(format_args!("Failed to start s3 stream")),
);
let rejected_value = JSPromise::rejected_promise(
global_this,
global_this.create_error_instance(format_args!("Failed to start s3 stream")),
)
.to_js();
// HTTPRequestBody has no Drop impl, so a bare `drop(body)` would
// leak the S3 Blob.Store ref.
body.detach();
Expand Down Expand Up @@ -1710,11 +1646,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
let opened_fd = match opened_fd_res {
Err(err) => {
let err_js = err.to_js(global_this);
let rejected_value =
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err_js,
);
let rejected_value = JSPromise::rejected_promise(global_this, err_js).to_js();
return Ok(rejected_value);
}
Ok(fd) => fd,
Expand Down Expand Up @@ -1806,10 +1738,7 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
match res {
Err(err) => {
let rejected_value =
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
err.to_js(global_this),
);
JSPromise::rejected_promise(global_this, err.to_js(global_this)).to_js();
body.detach();
return Ok(rejected_value);
}
Expand Down Expand Up @@ -1898,14 +1827,13 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
// `defer body.ReadableStream.deinit()` → Drop on `body` scope exit.

if method != Method::PUT && method != Method::POST {
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
global_this.create_error_instance(format_args!(
"Only POST and PUT do support body when using S3"
)),
),
);
return Ok(JSPromise::rejected_promise(
global_this,
global_this.create_error_instance(format_args!(
"Only POST and PUT do support body when using S3"
)),
)
.to_js());
}
let promise = jsc::JSPromiseStrong::init(global_this);
let promise_value = promise.value();
Expand Down Expand Up @@ -1979,12 +1907,11 @@ fn fetch_impl<const ALLOW_GET_BODY: bool>(
) {
Ok(r) => r,
Err(sign_err) => {
return Ok(
JSPromise::dangerously_create_rejected_promise_value_without_notifying_vm(
global_this,
s3::get_js_sign_error(sign_err.into(), global_this),
),
);
return Ok(JSPromise::rejected_promise(
global_this,
s3::get_js_sign_error(sign_err.into(), global_this),
)
.to_js());
}
};
// `defer result.deinit()` → Drop.
Expand Down
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