[processor/transform] Fix panic on gauge type (#13907)

* fix panic for gauge data types in transformprocessor

* add changelog entry

processor/transformprocessor/internal/metrics/processor.go

@@ -54,7 +54,7 @@ func (p *Processor) ProcessMetrics(_ context.Context, td pmetric.Metrics) (pmetr
  case pmetric.MetricDataTypeSum:
  p.handleNumberDataPoints(metric.Sum().DataPoints(), metrics.At(k), metrics, smetrics.Scope(), rmetrics.Resource())
  case pmetric.MetricDataTypeGauge:
- p.handleNumberDataPoints(metric.Sum().DataPoints(), metrics.At(k), metrics, smetrics.Scope(), rmetrics.Resource())
+ p.handleNumberDataPoints(metric.Gauge().DataPoints(), metrics.At(k), metrics, smetrics.Scope(), rmetrics.Resource())
  case pmetric.MetricDataTypeHistogram:
  p.handleHistogramDataPoints(metric.Histogram().DataPoints(), metrics.At(k), metrics, smetrics.Scope(), rmetrics.Resource())
  case pmetric.MetricDataTypeExponentialHistogram:

unreleased/transform-fix-panic-gauge-type.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: transformprocessor
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fixes panic of transformprocessor handling Gauge types
+
+# One or more tracking issues related to the change
+issues: [13905]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: