Fix crash in logging when log files are not writable (#286)

* Addresses null pointer crash in logging when log files are not writable

* One of these days, I'll be able to type code without spotless complaining.

But today is not that day.

photon-core/src/main/java/org/photonvision/common/logging/Logger.java

@@ -344,6 +344,8 @@ public class Logger {
                 wantsFlush = true;
             } catch (IOException e) {
                 e.printStackTrace();
+            } catch (NullPointerException e) {
+                // Nothing to do - no stream available for writing
             }
         }
     }