add completions in assert stmt - fixes #24888

pkg/analysis_server/lib/src/services/completion/optype.dart

Index: pkg/analysis_server/lib/src/services/completion/optype.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/optype.dart b/pkg/analysis_server/lib/src/services/completion/optype.dart
index 3408e9637717eb4ca7685ab74036d5817f6ad8a7..768b0d3e54b9f64bbe49c2f8eee63f99cd7a9326 100644
--- a/pkg/analysis_server/lib/src/services/completion/optype.dart
+++ b/pkg/analysis_server/lib/src/services/completion/optype.dart
@@ -129,6 +129,14 @@ class _OpTypeAstVisitor extends GeneralizingAstVisitor {
     }
   }
 
+@override
+  void visitAssertStatement(AssertStatement node) {
+    if (identical(entity, node.condition)) {
+      optype.includeReturnValueSuggestions = true;
+      optype.includeTypeNameSuggestions = true;
+    }
+  }
+
   void visitAssignmentExpression(AssignmentExpression node) {
     if (identical(entity, node.rightHandSide)) {
       optype.includeReturnValueSuggestions = true;