[Metricbeat] windows.perfmon - No error, but error.message added to event

[tammytorbert]

Bug - error.message populated, but no error generated by perfmon query.

For confirmed bugs, please report:

• Version: Elastic 8.12.2 / Windows Integration v 1.44.3
• Operating System: Windows Server 2022
• Discuss Forum URL: Internal Slack URL - https://elastic.slack.com/archives/C010LT16CFR/p1710509993651259
• Steps to Reproduce:

Configure Windows Integration with perfmon query like the following:

- object: 'Process'
  instance: ["*"]
  counters:
   - name: '% Processor Time'
     field: cpu_perc
     format: "float"
- object: 'Memory'
  counters: 
   - name: 'Available MBytes'
     field: memory_available_mbytes
     format: "float"
   - name: 'Pages/sec'
     field: memory_pages_sec
     format: "float"

On collection, following will be captured in the error.message field:
failed on query=\\TT-WINHOST1\Memory\Pages/sec: %!w(<nil>)

In discussion with @andrewkroh - mentioned the error should be conditional.

diff --git a/metricbeat/module/windows/perfmon/data.go b/metricbeat/module/windows/perfmon/data.go
index 9add5c0389..f5747888d7 100644
--- a/metricbeat/module/windows/perfmon/data.go
+++ b/metricbeat/module/windows/perfmon/data.go
@@ -69,7 +69,9 @@ func (re *Reader) groupToEvents(counters map[string][]pdh.CounterValue) []mb.Eve
 			if _, ok := eventMap[eventKey]; !ok {
 				eventMap[eventKey] = &mb.Event{
 					MetricSetFields: mapstr.M{},
-					Error:           fmt.Errorf("failed on query=%v: %w", counterPath, val.Err.Error),
+				}
+				if val.Err.Error != nil {
+					eventMap[eventKey].Error = fmt.Errorf("failed on query=%v: %w", counterPath, val.Err.Error)
 				}
 				if val.Instance != "" {
 					// will ignore instance index

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)

[botelastic]

This issue doesn't have a Team:<team> label.

[cmacknz]

Thanks, also reported in #38140

[cmacknz]

Closing as a duplicate.