Improved error descriptions when the error itself is not logged.

Author: rkistner

packages/powersync/lib/src/streaming_sync.dart

@@ -63,7 +63,8 @@ class StreamingSyncImplementation {
         await streamingSyncIteration();
         // Continue immediately
       } catch (e, stacktrace) {
-        log.warning('Sync error', e, stacktrace);
+        final message = _syncErrorMessage(e);
+        log.warning('Sync error: $message', e, stacktrace);
         invalidCredentials = true;
 
         _updateStatus(
@@ -124,7 +125,7 @@ class StreamingSyncImplementation {
   Future<String> getWriteCheckpoint() async {
     final credentials = await credentialsCallback();
     if (credentials == null) {
-      throw AssertionError("Not logged in");
+      throw CredentialsException("Not logged in");
     }
     final uri = credentials.endpointUri('write-checkpoint2.json');
 
@@ -139,7 +140,7 @@ class StreamingSyncImplementation {
       }
     }
     if (response.statusCode != 200) {
-      throw getError(response);
+      throw _getError(response);
     }
 
     final body = convert.jsonDecode(response.body);
@@ -237,7 +238,8 @@ class StreamingSyncImplementation {
       } else if (line is StreamingSyncCheckpointDiff) {
         // TODO: It may be faster to just keep track of the diff, instead of the entire checkpoint
         if (targetCheckpoint == null) {
-          throw AssertionError('Checkpoint diff without previous checkpoint');
+          throw PowerSyncProtocolException(
+              'Checkpoint diff without previous checkpoint');
         }
         final diff = line;
         final Map<String, BucketChecksum> newBuckets = {};
@@ -322,7 +324,7 @@ class StreamingSyncImplementation {
   Stream<Object?> streamingSyncRequest(StreamingSyncRequest data) async* {
     final credentials = await credentialsCallback();
     if (credentials == null) {
-      throw AssertionError('Not logged in');
+      throw CredentialsException('Not logged in');
     }
     final uri = credentials.endpointUri('sync/stream');
 
@@ -339,7 +341,7 @@ class StreamingSyncImplementation {
       }
     }
     if (res.statusCode != 200) {
-      throw await getStreamedError(res);
+      throw await _getStreamedError(res);
     }
 
     // Note: The response stream is automatically closed when this loop errors
@@ -349,33 +351,38 @@ class StreamingSyncImplementation {
   }
 }
 
-HttpException getError(http.Response response) {
+SyncResponseException _getError(http.Response response) {
   try {
     final body = response.body;
     final decoded = convert.jsonDecode(body);
-    final details = stringOrFirst(decoded['error']?['details']) ?? body;
+    final details = _stringOrFirst(decoded['error']?['details']) ?? body;
     final message = '${response.reasonPhrase ?? "Request failed"}: $details';
-    return HttpException(message, uri: response.request?.url);
+    return SyncResponseException(response.statusCode, message);
   } on Error catch (_) {
-    return HttpException(response.reasonPhrase ?? "Request failed",
-        uri: response.request?.url);
+    return SyncResponseException(
+      response.statusCode,
+      response.reasonPhrase ?? "Request failed",
+    );
   }
 }
 
-Future<HttpException> getStreamedError(http.StreamedResponse response) async {
+Future<SyncResponseException> _getStreamedError(
+    http.StreamedResponse response) async {
   try {
     final body = await response.stream.bytesToString();
     final decoded = convert.jsonDecode(body);
-    final details = stringOrFirst(decoded['error']?['details']) ?? body;
+    final details = _stringOrFirst(decoded['error']?['details']) ?? body;
     final message = '${response.reasonPhrase ?? "Request failed"}: $details';
-    return HttpException(message, uri: response.request?.url);
+    return SyncResponseException(response.statusCode, message);
   } on Error catch (_) {
-    return HttpException(response.reasonPhrase ?? "Request failed",
-        uri: response.request?.url);
+    return SyncResponseException(
+      response.statusCode,
+      response.reasonPhrase ?? "Request failed",
+    );
   }
 }
 
-String? stringOrFirst(Object? details) {
+String? _stringOrFirst(Object? details) {
   if (details == null) {
     return null;
   } else if (details is String) {
@@ -386,3 +393,63 @@ String? stringOrFirst(Object? details) {
     return null;
   }
 }
+
+/// Attempt to give a basic summary of the error for cases where the full error
+/// is not logged.
+String _syncErrorMessage(Object? error) {
+  if (error == null) {
+    return 'Unknown';
+  } else if (error is HttpException) {
+    return 'Sync service error';
+  } else if (error is SyncResponseException) {
+    if (error.statusCode == 401) {
+      return 'Authorization error';
+    } else {
+      return 'Sync service error';
+    }
+  } else if (error is SocketException) {
+    return 'Connection error';
+  } else if (error is ArgumentError || error is FormatException) {
+    return 'Configuration error';
+  } else if (error is CredentialsException) {
+    return 'Credentials error';
+  } else if (error is PowerSyncProtocolException) {
+    return 'Protocol error';
+  } else {
+    return '${error.runtimeType}';
+  }
+}
+
+class CredentialsException implements Exception {
+  String message;
+
+  CredentialsException(this.message);
+
+  @override
+  toString() {
+    return 'CredentialsException: $message';
+  }
+}
+
+class PowerSyncProtocolException implements Exception {
+  String message;
+
+  PowerSyncProtocolException(this.message);
+
+  @override
+  toString() {
+    return 'SyncProtocolException: $message';
+  }
+}
+
+class SyncResponseException implements Exception {
+  int statusCode;
+  String description;
+
+  SyncResponseException(this.statusCode, this.description);
+
+  @override
+  toString() {
+    return 'SyncResponseException: $statusCode $description';
+  }
+}