Small change to return error from periodic exporter

opentelemetry-sdk/CHANGELOG.md

@@ -45,6 +45,8 @@
 
 - **Breaking** [1850] (https://github.com/open-telemetry/opentelemetry-rust/pull/1850) `LoggerProvider::log_processors()` and `LoggerProvider::resource()` are not public methods anymore. They are only used within the `opentelemetry-sdk` crate.
 
+- [1857](https://github.com/open-telemetry/opentelemetry-rust/pull/1857) Fixed an issue in the `collect_and_export()` method of the periodic exporter where errors during export were dropped, ensuring proper error handling and reporting. 
+
 ## v0.23.0
 
 - Fix SimpleSpanProcessor to be consistent with log counterpart. Also removed

opentelemetry-sdk/src/metrics/periodic_reader.rs

@@ -260,7 +260,7 @@ impl<RT: Runtime> PeriodicReaderWorker<RT> {
         pin_mut!(timeout);
 
         match future::select(export, timeout).await {
-            Either::Left(_) => Ok(()),
+            Either::Left((res, _)) => res, // return the result.
             Either::Right(_) => Err(MetricsError::Other("export timed out".into())),
         }
     }