Add error log for gauge delta temporality.

Author: uuzay

sdk/src/metrics/state/metric_collector.cc

@@ -35,7 +35,14 @@ MetricCollector::MetricCollector(opentelemetry::sdk::metrics::MeterContext *cont
 AggregationTemporality MetricCollector::GetAggregationTemporality(
     InstrumentType instrument_type) noexcept
 {
-  return metric_reader_->GetAggregationTemporality(instrument_type);
+  auto aggregation_temporality = metric_reader_->GetAggregationTemporality(instrument_type);
+  if(aggregation_temporality == AggregationTemporality::kDelta && instrument_type == InstrumentType::kGauge) { 
+    OTEL_INTERNAL_LOG_ERROR("[MetricCollector::GetAggregationTemporality] - Error getting aggregation temporality."
+                            << "Delta temporality for Synchronous Gauge is currently not supported, using cumulative temporality");
+    
+    return AggregationTemporality::kCumulative;
+  }
+  return aggregation_temporality;
 }
 
 bool MetricCollector::Collect(