Fix syntax error in generated code with empty primary key

moor/pubspec.yaml

@@ -1,6 +1,6 @@
 name: moor
 description: Moor is a safe and reactive persistence library for Dart applications
-version: 1.3.0
+version: 1.3.1
 homepage: https://github.com/simolus3/moor
 authors:
   - Simon Binder <simolus3@gmail.com>

moor/test/data/tables/todos.dart

@@ -47,9 +47,7 @@ class SharedTodos extends Table {
 }
 
 class TableWithoutPK extends Table {
-
   IntColumn get notReallyAnId => integer()();
-
 }
 
 @UseMoor(tables: [TodosTable, Categories, Users, SharedTodos, TableWithoutPK])

moor/test/data/tables/todos.g.dart

@@ -716,7 +716,7 @@ class $TableWithoutPKTable extends TableWithoutPK
   bool validateIntegrity(TableWithoutPKData instance, bool isInserting) =>
       notReallyAnId.isAcceptableValue(instance.notReallyAnId, isInserting);
   @override
-  Set<GeneratedColumn> get $primaryKey => {};
+  Set<GeneratedColumn> get $primaryKey => <GeneratedColumn>{};
   @override
   TableWithoutPKData map(Map<String, dynamic> data, {String tablePrefix}) {
     final effectivePrefix = tablePrefix != null ? '$tablePrefix.' : null;

moor_generator/lib/src/writer/table_writer.dart

@@ -175,8 +175,8 @@ class TableWriter {
     // explicitly defined as PK, but with AI this happens implicitly.
     primaryKey ??= table.columns.where((c) => c.hasAI).toSet();
 
-    if (primaryKey == null) {
-      buffer.write('null;');
+    if (primaryKey.isEmpty) {
+      buffer.write('<GeneratedColumn>{};');
       return;
     }
 

moor_generator/pubspec.yaml

@@ -1,6 +1,6 @@
 name: moor_generator
 description: Dev-dependency to generate table and dataclasses together with the moor package.
-version: 1.3.0
+version: 1.3.1
 homepage: https://github.com/simolus3/moor
 authors:
   - Simon Binder <simolus3@gmail.com>