flush() is only called if the stream is open

This ensures flush() is only called if the stream is open, and logs (but ignores) any exceptions during flush. This should prevent the "Bad file descriptor" error.

I see this error a lot on a rak unit, I dont know this is the way but .. you be the judge.

Author: SpudGunMan

meshtastic/serial_interface.py

@@ -85,10 +85,14 @@ def __repr__(self):
 
     def close(self) -> None:
         """Close a connection to the device"""
-        if self.stream:  # Stream can be null if we were already closed
-            self.stream.flush()  # FIXME: why are there these  two flushes with 100ms sleeps?  This shouldn't be necessary
-            time.sleep(0.1)
-            self.stream.flush()
-            time.sleep(0.1)
+        if hasattr(self, "stream") and self.stream and getattr(self.stream, "is_open", False):
+            try:
+                self.stream.flush()
+                time.sleep(0.1)
+                # FIXME: why are there these  two flushes with 100ms sleeps?  This shouldn't be necessary
+                self.stream.flush()
+                time.sleep(0.1)
+            except Exception as e:
+                logger.debug(f"Exception during flush: {e}")
         logger.debug("Closing Serial stream")
         StreamInterface.close(self)