child_process: reduce abort handler code duplication

Move duplicate abort handler logic into a separate function.

PR-URL: #36644
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

lib/child_process.js

@@ -354,6 +354,12 @@ function execFile(file /* , args, options, callback */) {
     }
   }
 
+  function abortHandler() {
+    if (!ex)
+      ex = new AbortError();
+    process.nextTick(() => kill());
+  }
+
   if (options.timeout > 0) {
     timeoutId = setTimeout(function delayedKill() {
       kill();
@@ -362,16 +368,11 @@ function execFile(file /* , args, options, callback */) {
   }
   if (options.signal) {
     if (options.signal.aborted) {
-      if (!ex)
-        ex = new AbortError();
-      process.nextTick(() => kill());
+      process.nextTick(abortHandler);
     } else {
       const childController = new AbortController();
-      options.signal.addEventListener('abort', () => {
-        if (!ex)
-          ex = new AbortError();
-        kill();
-      }, { signal: childController.signal });
+      options.signal.addEventListener('abort', abortHandler,
+                                      { signal: childController.signal });
       child.once('close', () => childController.abort());
     }
   }