upd again

example/lib/main.dart

@@ -43,6 +43,7 @@ ${e.cause}
   ${e.cause.name}
   ${e.cause.cause}
   ${e.cause.message}
+  ${e.cause.fields}
 ${e.message}
 $e
 ''');

lib/deno_postgres_interop.dart

@@ -9,6 +9,7 @@ export 'src/command_type.dart';
 export 'src/connection.dart';
 export 'src/connection_options.dart';
 export 'src/encoded_arg.dart';
+export 'src/errors/postgres_error.dart';
 export 'src/errors/transaction_error.dart';
 export 'src/isolation_level.dart';
 export 'src/notice.dart';

lib/src/errors/connection_error.dart

@@ -0,0 +1,7 @@
+import 'dart:js_interop';
+
+import 'package:deno_postgres_interop/src/errors/js_error.dart';
+
+/// [js/Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error).
+@JS('Error')
+class ConnectionError extends JSError {}

lib/src/errors/connection_params_error.dart

@@ -0,0 +1,7 @@
+import 'dart:js_interop';
+
+import 'package:deno_postgres_interop/src/errors/js_error.dart';
+
+/// [js/Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error).
+@JS('Error')
+class ConnectionParamsError extends JSError {}

lib/src/errors/postgres_error.dart

@@ -1,6 +1,11 @@
 import 'dart:js_interop';
 
 import 'package:deno_postgres_interop/src/errors/js_error.dart';
+import 'package:deno_postgres_interop/src/notice.dart';
 
+/// [deno-postgres@v0.17.0/PostgresError](https://deno.land/x/postgres@v0.17.0/client/error.ts?s=TransactionError).
 @JS()
-class PostgresError extends JSError {}
+class PostgresError extends JSError {
+  /// [deno-postgres@v0.17.0/PostgresError](https://deno.land/x/postgres@v0.17.0/client/error.ts?s=PostgresError#prop_fields).
+  external Notice get fields;
+}