refactor: clean up composeSignals early-return structure (#10844)

Flips the main if-block to an early-return pattern to reduce nesting.
Explicitly initializes aborted to false. Adds a guard clause in
unsubscribe to avoid duplicate cleanup.

Preserves the existing manual event-listener approach because
AbortSignal.any() introduces event-loop timing differences that
break fetch adapter stream-abort tests.

Closes #10815.

Co-authored-by: mixelburg <mixelburg@gmail.com>
Co-authored-by: Jay <jasonsaayman@gmail.com>

lib/helpers/composeSignals.js

@@ -3,54 +3,55 @@ import AxiosError from '../core/AxiosError.js';
 import utils from '../utils.js';
 
 const composeSignals = (signals, timeout) => {
-  const { length } = (signals = signals ? signals.filter(Boolean) : []);
+  signals = signals ? signals.filter(Boolean) : [];
 
-  if (timeout || length) {
+  if (!timeout && !signals.length) {
-    let controller = new AbortController();
+    return;
-
-    let aborted;
-
-    const onabort = function (reason) {
-      if (!aborted) {
-        aborted = true;
-        unsubscribe();
-        const err = reason instanceof Error ? reason : this.reason;
-        controller.abort(
-          err instanceof AxiosError
-            ? err
-            : new CanceledError(err instanceof Error ? err.message : err)
-        );
-      }
-    };
-
-    let timer =
-      timeout &&
-      setTimeout(() => {
-        timer = null;
-        onabort(new AxiosError(`timeout of ${timeout}ms exceeded`, AxiosError.ETIMEDOUT));
-      }, timeout);
-
-    const unsubscribe = () => {
-      if (signals) {
-        timer && clearTimeout(timer);
-        timer = null;
-        signals.forEach((signal) => {
-          signal.unsubscribe
-            ? signal.unsubscribe(onabort)
-            : signal.removeEventListener('abort', onabort);
-        });
-        signals = null;
-      }
-    };
-
-    signals.forEach((signal) => signal.addEventListener('abort', onabort));
-
-    const { signal } = controller;
-
-    signal.unsubscribe = () => utils.asap(unsubscribe);
-
-    return signal;
   }
+
+  const controller = new AbortController();
+
+  let aborted = false;
+
+  const onabort = function (reason) {
+    if (!aborted) {
+      aborted = true;
+      unsubscribe();
+      const err = reason instanceof Error ? reason : this.reason;
+      controller.abort(
+        err instanceof AxiosError
+          ? err
+          : new CanceledError(err instanceof Error ? err.message : err)
+      );
+    }
+  };
+
+  let timer =
+    timeout &&
+    setTimeout(() => {
+      timer = null;
+      onabort(new AxiosError(`timeout of ${timeout}ms exceeded`, AxiosError.ETIMEDOUT));
+    }, timeout);
+
+  const unsubscribe = () => {
+    if (!signals) { return; }
+    timer && clearTimeout(timer);
+    timer = null;
+    signals.forEach((signal) => {
+      signal.unsubscribe
+        ? signal.unsubscribe(onabort)
+        : signal.removeEventListener('abort', onabort);
+    });
+    signals = null;
+  };
+
+  signals.forEach((signal) => signal.addEventListener('abort', onabort));
+
+  const { signal } = controller;
+
+  signal.unsubscribe = () => utils.asap(unsubscribe);
+
+  return signal;
 };
 
 export default composeSignals;