initial commit with cache support & example

packages/fl_query/lib/src/exceptions/network.dart

@@ -0,0 +1,32 @@
+import 'package:http/http.dart' as http show ClientException;
+
+/// Exception occurring when there is a network-level error
+class NetworkException extends LinkException {
+  NetworkException({
+    dynamic originalException,
+    this.message,
+    required this.uri,
+  }) : super(originalException);
+
+  final String? message;
+  final Uri? uri;
+
+  String toString() =>
+      'Failed to connect to $uri: ${message ?? originalException}';
+}
+
+/// We wrap [base.translateFailure] to handle io-specific network errors.
+///
+/// Once `gql_link` has robust http and socket exception handling,
+/// this and `./network.dart` can be removed and `./exceptions_next.dart`
+/// will be all that is necessary
+NetworkException? translateFailure(dynamic failure) {
+  if (failure is http.ClientException) {
+    return NetworkException(
+      originalException: failure,
+      message: failure.message,
+      uri: failure.uri,
+    );
+  }
+  return null;
+}