add assersion on match

Author: dshukertjr

packages/postgrest/lib/src/postgrest_filter_builder.dart

@@ -67,7 +67,7 @@ class PostgrestFilterBuilder<T> extends PostgrestTransformBuilder<T> {
   ///     .eq('username', 'supabot');
   /// ```
   ///
-  /// If you want to filter with null equality, use [isFilter] instead.
+  /// For `null` equality, use [isFilter] instead.
   PostgrestFilterBuilder<T> eq(String column, Object value) {
     final Uri url;
     if (value is List) {
@@ -479,7 +479,9 @@ class PostgrestFilterBuilder<T> extends PostgrestTransformBuilder<T> {
   ///   'status': 'ONLINE',
   /// });
   /// ```
-  PostgrestFilterBuilder<T> match(Map<String, Object> query) {
+  PostgrestFilterBuilder<T> match(Map query) {
+    assert(!query.values.contains(null),
+        '`null` equality does not work with match. Use isFilter instead.');
     var url = _url;
     query.forEach((k, v) => url = appendSearchParams(k, 'eq.$v', url));
     return copyWithUrl(url);