[logging] Corrects intercept of ECONNRESET (elastic#31742)

errno is not set for ECONNRESET

https://github.com/hapijs/wreck/blob/29d8f4b5eaa12c5d44c642130cd6002c1d83ffd2/lib/index.js#L290

Closes elastic#22225

Example:

{ Error: socket hang up
  at TLSSocket.onSocketClose (_tls_wrap.js:761:23)
  at TLSSocket.emit (events.js:194:15)
  at _handle.close (net.js:600:12)
  at Socket.done (_tls_wrap.js:388:7)
  at Object.onceWrapper (events.js:277:13)
  at Socket.emit (events.js:189:13)
  at TCP._handle.close (net.js:600:12) code: 'ECONNRESET'

Signed-off-by: Tyler Smalley <tyler.smalley@elastic.co>

src/legacy/server/logging/log_interceptor.js

@@ -32,11 +32,13 @@ function doesMessageMatch(errorMessage, match) {
   if (isRegExp) return match.test(errorMessage);
   return errorMessage === match;
 }
+
 // converts the given event into a debug log if it's an error of the given type
-function downgradeIfErrorType(errorType, event, field = 'errno') {
+function downgradeIfErrorType(errorType, event) {
   const isClientError = doTagsMatch(event, ['connection', 'client', 'error']);
-  const matchesErrorType = isClientError && get(event, `error.${field}`) === errorType;
+  if (!isClientError) return null;
 
+  const matchesErrorType = get(event, 'error.code') === errorType || get(event, 'error.errno') === errorType;
   if (!matchesErrorType) return null;
 
   const errorTypeTag = errorType.toLowerCase();
@@ -117,7 +119,7 @@ export class LogInterceptor extends Stream.Transform {
   }
 
   downgradeIfHTTPSWhenHTTP(event) {
-    return downgradeIfErrorType('HPE_INVALID_METHOD', event, 'code');
+    return downgradeIfErrorType('HPE_INVALID_METHOD', event);
   }
 
   downgradeIfHTTPWhenHTTPS(event) {

src/legacy/server/logging/log_interceptor.test.js

@@ -31,7 +31,7 @@ function stubClientErrorEvent(errorMeta) {
   };
 }
 
-const stubEconnresetEvent = () => stubClientErrorEvent({ errno: 'ECONNRESET' });
+const stubEconnresetEvent = () => stubClientErrorEvent({ code: 'ECONNRESET' });
 const stubEpipeEvent = () => stubClientErrorEvent({ errno: 'EPIPE' });
 const stubEcanceledEvent = () => stubClientErrorEvent({ errno: 'ECANCELED' });