trivial functional expression fix for empty lambda code block

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/trivialFunctionalExpressionUsage/afterEmptyCodeBlock.java

@@ -0,0 +1,7 @@
+// "Replace method call on lambda with lambda body" "true"
+
+
+public class Main {
+  void test() {
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/trivialFunctionalExpressionUsage/beforeEmptyCodeBlock.java

@@ -0,0 +1,8 @@
+// "Replace method call on lambda with lambda body" "true"
+
+
+public class Main {
+  void test() {
+    ((Runnable) () -> {}).ru<caret>n();
+  }
+}

plugins/InspectionGadgets/src/com/intellij/codeInspection/TrivialFunctionalExpressionUsageInspection.java

@@ -231,14 +231,16 @@ public class TrivialFunctionalExpressionUsageInspection extends BaseJavaBatchLoc
     body = element.getBody();
     final PsiElement parent = callExpression.getParent();
     final PsiStatement[] statements = ((PsiCodeBlock)body).getStatements();
-    if (statements.length == 0) return;
-    final PsiStatement anchor = PsiTreeUtil.getParentOfType(parent, PsiStatement.class, false);
-    PsiReturnStatement statement = ObjectUtils.tryCast(statements[statements.length - 1], PsiReturnStatement.class);
-    if (anchor != null) {
-      final PsiElement gParent = anchor.getParent();
-      for (PsiElement child : body.getChildren()) {
-        if (child != statement && !(child instanceof PsiJavaToken)) {
-          gParent.addBefore(ct.markUnchanged(child), anchor);
+    PsiReturnStatement statement = null;
+    if (statements.length > 0) {
+      final PsiStatement anchor = PsiTreeUtil.getParentOfType(parent, PsiStatement.class, false);
+      statement = ObjectUtils.tryCast(statements[statements.length - 1], PsiReturnStatement.class);
+      if (anchor != null) {
+        final PsiElement gParent = anchor.getParent();
+        for (PsiElement child : body.getChildren()) {
+          if (child != statement && !(child instanceof PsiJavaToken)) {
+            gParent.addBefore(ct.markUnchanged(child), anchor);
+          }
         }
       }
     }