chore: cleanup MetadataInjector

hello-tracing-common/src/otel/grpc.rs

@@ -3,7 +3,7 @@ use tonic::{
     metadata::{MetadataKey, MetadataMap, MetadataValue},
     Request, Status,
 };
-use tracing::{error, Span};
+use tracing::{warn, Span};
 use tracing_opentelemetry::OpenTelemetrySpanExt;
 
 /// Trace context propagation: send the trace context by injecting it into the metadata of the given
@@ -22,23 +22,15 @@ struct MetadataInjector<'a>(&'a mut MetadataMap);
 impl Injector for MetadataInjector<'_> {
     fn set(&mut self, key: &str, value: String) {
         match MetadataKey::from_bytes(key.as_bytes()) {
-            Ok(name) => match MetadataValue::try_from(&value) {
+            Ok(key) => match MetadataValue::try_from(&value) {
                 Ok(value) => {
-                    self.0.insert(name, value);
+                    self.0.insert(key, value);
                 }
 
-                Err(error) => error!(
-                    value,
-                    error = format!("{error:#}"),
-                    "parse value as metadata value"
-                ),
+                Err(error) => warn!(value, error = format!("{error:#}"), "parse metadata value"),
             },
 
-            Err(error) => error!(
-                key,
-                error = format!("{error:#}"),
-                "parse key as metadata value"
-            ),
+            Err(error) => warn!(key, error = format!("{error:#}"), "parse metadata key"),
         }
     }
 }