src: fix coverity warnings in node_file.cc

Fix two warnings about a useless call and not checking
a return value.

Signed-off-by: Michael Dawson <mdawson@devrus.com>

PR-URL: #42272
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>

Author: mhdawson

src/node_file.cc

@@ -277,13 +277,13 @@ inline void FileHandle::Close() {
                        detail.fd);
     if (env->filehandle_close_warning()) {
       env->set_filehandle_close_warning(false);
-      ProcessEmitDeprecationWarning(
+      USE(ProcessEmitDeprecationWarning(
           env,
           "Closing a FileHandle object on garbage collection is deprecated. "
           "Please close FileHandle objects explicitly using "
           "FileHandle.prototype.close(). In the future, an error will be "
           "thrown if a file descriptor is closed during garbage collection.",
-          "DEP0137").IsNothing();
+          "DEP0137"));
     }
   }, CallbackFlags::kUnrefed);
 }