Issue 25252. Stop collecting covering expressions at void invocations.

pkg/analysis_server/lib/src/services/refactoring/extract_local.dart

Index: pkg/analysis_server/lib/src/services/refactoring/extract_local.dart
diff --git a/pkg/analysis_server/lib/src/services/refactoring/extract_local.dart b/pkg/analysis_server/lib/src/services/refactoring/extract_local.dart
index cd35e64da8e4573902ce5270da7ebb6698bff9d8..d24ccd9496fd17b61079ae5cc72f613ccd6a2e9f 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/extract_local.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/extract_local.dart
@@ -232,6 +232,21 @@ class ExtractLocalRefactoringImpl extends RefactoringImpl
         node is Expression || node is ArgumentList;
         node = node.parent) {
       AstNode parent = node.parent;
+      // stop at void method invocations
+      if (node is MethodInvocation) {
+        MethodInvocation invocation = node;
+        Element element = invocation.methodName.bestElement;
+        if (element is ExecutableElement &&
+            element.returnType != null &&
+            element.returnType.isVoid) {
+          if (rootExpression == null) {
+            return new RefactoringStatus.fatal(
+                'Cannot extract the void expression.',
+                newLocation_fromNode(node));
+          }
+          break;
+        }
+      }
       // skip ArgumentList
       if (node is ArgumentList) {
         continue;