LogReader: fix plotjuggler not reading properly (#31023)

* fix plotjuggler

* simpler

* fix juggler

* fix that
old-commit-hash: 61fe705160

tools/plotjuggler/test_plotjuggler.py

@@ -31,6 +31,8 @@ class TestPlotJuggler(unittest.TestCase):
       self.assertEqual(p.poll(), None)
       os.killpg(os.getpgid(p.pid), signal.SIGTERM)
 
+      self.assertNotIn("Raw file read failed", output)
+
   # TODO: also test that layouts successfully load
   def test_layouts(self):
     bad_strings = (