Enhance testing and error handling; update documentation and examples

examples/raspberry_pi_pico.py

@@ -16,13 +16,19 @@ def on_packet(packet):
     if packet.WhichOneof("payload_variant") != "decoded":
         return
     if packet.decoded.portnum == PortNum.TEXT_MESSAGE_APP:
-        print("from !%08x: %s" % (
-            packet.from_, packet.decoded.payload.decode("utf-8", "replace")
-        ))
+        try:
+            text = packet.decoded.payload.decode("utf-8")
+        except UnicodeError:
+            text = repr(packet.decoded.payload)
+        print("from !%08x: %s" % (packet.from_, text))
+
+
+def on_error(error, payload):
+    print("skipping undecodable radio frame:", error, "(%d bytes)" % len(payload))
 
 
 uart = UART(0, 115200, tx=Pin(0), rx=Pin(1), timeout=0, rxbuf=1024)
-mesh = SerialInterface(uart, on_packet=on_packet, on_log=print)
+mesh = SerialInterface(uart, on_packet=on_packet, on_log=print, on_error=on_error)
 mesh.connect()
 
 hello_sent = False