Fix some issues found by coverity scans on Node.js

third_party/WebKit/Source/platform/inspector_protocol/ValueConversions.h

Index: third_party/WebKit/Source/platform/inspector_protocol/ValueConversions.h
diff --git a/third_party/WebKit/Source/platform/inspector_protocol/ValueConversions.h b/third_party/WebKit/Source/platform/inspector_protocol/ValueConversions.h
index b82f04f588f7f1e7fe070fd1a7922b54c17e6716..df72ed8414f88c56c41cac54026cd3db182c39f5 100644
--- a/third_party/WebKit/Source/platform/inspector_protocol/ValueConversions.h
+++ b/third_party/WebKit/Source/platform/inspector_protocol/ValueConversions.h
@@ -112,8 +112,10 @@ struct FromValue<Value> {
     static std::unique_ptr<Value> parse(protocol::Value* value, ErrorSupport* errors)
     {
         bool success = !!value;
-        if (!success)
+        if (!success) {
             errors->addError("value expected");
+            return nullptr;
+        }
         return value->clone();
     }
 };