fix: Increase resilience to characteristic read errors

Discovery of a peripheral's services should not error out merely because
one of the characteristics encountered an "AccessDenied" or similar
error

Author: DavidZemon

src/winrtble/ble/device.rs

@@ -100,15 +100,27 @@ impl BLEDevice {
         let async_result = service
             .GetCharacteristicsWithCacheModeAsync(BluetoothCacheMode::Uncached)?
             .await?;
-        let status = async_result.Status();
-        if status == Ok(GattCommunicationStatus::Success) {
-            let results = async_result.Characteristics()?;
-            debug!("characteristics {:?}", results.Size());
-            Ok(results.into_iter().collect())
-        } else {
-            Err(Error::Other(
-                format!("get_characteristics for {:?} failed: {:?}", service, status).into(),
-            ))
+
+        match async_result.Status() {
+            Ok(GattCommunicationStatus::Success) => {
+                let results = async_result.Characteristics()?;
+                debug!("characteristics {:?}", results.Size());
+                Ok(results.into_iter().collect())
+            }
+            Ok(GattCommunicationStatus::ProtocolError) => Err(Error::Other(
+                format!(
+                    "get_characteristics for {:?} encountered a protocol error",
+                    service
+                )
+                .into(),
+            )),
+            Ok(status) => {
+                debug!("characteristic read failed due to {:?}", status);
+                Ok(vec![])
+            }
+            Err(e) => Err(Error::Other(
+                format!("get_characteristics for {:?} failed: {:?}", service, e).into(),
+            )),
         }
     }
 

src/winrtble/peripheral.rs

@@ -27,7 +27,7 @@ use crate::{
 use async_trait::async_trait;
 use dashmap::DashMap;
 use futures::stream::Stream;
-use log::{error, trace};
+use log::{trace, warn};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 #[cfg(feature = "serde")]
@@ -449,8 +449,7 @@ impl ApiPeripheral for Peripheral {
                             );
                         }
                         Err(e) => {
-                            error!("get_characteristics_async {:?}", e);
-                            return Err(e);
+                            warn!("get_characteristics_async {:?}", e);
                         }
                     }
                 }