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

@@ -3,12 +3,15 @@ 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) {
-    let controller = new AbortController();
+  if (!timeout && !signals.length) {
+    return;
+  }
 
-    let aborted;
+  const controller = new AbortController();
+
+  let aborted = false;
 
   const onabort = function (reason) {
     if (!aborted) {
@@ -31,7 +34,7 @@ const composeSignals = (signals, timeout) => {
     }, timeout);
 
   const unsubscribe = () => {
-      if (signals) {
+    if (!signals) { return; }
     timer && clearTimeout(timer);
     timer = null;
     signals.forEach((signal) => {
@@ -40,7 +43,6 @@ const composeSignals = (signals, timeout) => {
         : signal.removeEventListener('abort', onabort);
     });
     signals = null;
-      }
   };
 
   signals.forEach((signal) => signal.addEventListener('abort', onabort));
@@ -50,7 +52,6 @@ const composeSignals = (signals, timeout) => {
   signal.unsubscribe = () => utils.asap(unsubscribe);
 
   return signal;
-  }
 };
 
 export default composeSignals;