Prepare for adding InvalidType, make 'TypeChecker.isAssignableFromType()' null safe. (#666)

Author: scheglov

source_gen/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.3.2
+
+* Make `TypeChecker.isAssignableFromType()` null safe.
+
 ## 1.3.1
 
 * Always use a Uri in `part of` directives (previously a name would be used if

source_gen/lib/src/type_checker.dart

@@ -167,8 +167,10 @@ abstract class TypeChecker {
       (element is InterfaceElement && element.allSupertypes.any(isExactlyType));
 
   /// Returns `true` if [staticType] can be assigned to this type.
-  bool isAssignableFromType(DartType staticType) =>
-      isAssignableFrom(staticType.element!);
+  bool isAssignableFromType(DartType staticType) {
+    final element = staticType.element;
+    return element != null && isAssignableFrom(element);
+  }
 
   /// Returns `true` if representing the exact same class as [element].
   bool isExactly(Element element);

source_gen/pubspec.yaml

@@ -1,5 +1,5 @@
 name: source_gen
-version: 1.3.1
+version: 1.3.2
 description: >-
   Source code generation builders and utilities for the Dart build system
 repository: https://github.com/dart-lang/source_gen/tree/master/source_gen