ref(tracemetrics): Add more logging for internal reason (#5359)

Co-authored-by: Joris Bayer <[email protected]>

Author: k-fish

relay-server/src/processing/trace_metrics/mod.rs

@@ -61,10 +61,7 @@ impl crate::managed::OutcomeError for Error {
             Self::Filtered(f) => Some(Outcome::Filtered(f.clone())),
             Self::DuplicateContainer => Some(Outcome::Invalid(DiscardReason::DuplicateItem)),
             Self::ProcessingFailed(_) => {
-                relay_log::error!(
-                    error = &self as &dyn std::error::Error,
-                    "internal error: trace metric processing failed"
-                );
+                relay_log::error!("internal error: trace metric processing failed");
                 Some(Outcome::Invalid(DiscardReason::Internal))
             }
             Self::PiiConfig(_) => Some(Outcome::Invalid(DiscardReason::ProjectStatePii)),
@@ -151,7 +148,12 @@ impl Forward for TraceMetricOutput {
         self.0.try_map(|metrics, _| {
             metrics
                 .serialize_envelope()
-                .map_err(drop)
+                .map_err(|error| {
+                    relay_log::error!(
+                        error = %error,
+                        "internal error: failed to serialize trace metrics envelope"
+                    );
+                })
                 .with_outcome(Outcome::Invalid(DiscardReason::Internal))
         })
     }