Robustness fixes

client.py

@@ -22,15 +22,22 @@ LABEL_SIZE_DEFAULT = os.getenv('LABEL_SIZE_DEFAULT', '29x90')
 
 def print_label(image, printer=PRINTER_DEVICE, model=PRINTER_MODEL, label=LABEL_SIZE_DEFAULT):
     """Print the label directly using brother_ql module"""
+    import os
+    
     try:
+        # Check if printer device exists
+        if not os.path.exists(printer):
+            raise Exception(f"Printer device {printer} not found. Make sure the printer is powered on and connected via USB.")
+        
         qlr = BrotherQLRaster(model)
         qlr.exception_on_warning = True
         
         # Convert the PIL image to instructions
         instructions = convert(qlr=qlr, images=[image], label=label, cut=True)
         
-        # Send to printer
-        status = send(instructions=instructions, printer_identifier=printer, backend_identifier='linux_kernel', blocking=True)
+        # Send to printer using linux_kernel backend
+        print(f"Sending to printer: {printer}")
+        status = send(instructions=instructions, printer_identifier=f"file://{printer}", backend_identifier='linux_kernel', blocking=True)
         
         return status
     except Exception as e:
@@ -82,6 +89,29 @@ def on_message(client, userdata, msg):
             print("Printing label...")
             status = print_label(image, label=label_size)
             print(f"Print status: {status}")
+            
+            # Check for print errors
+            if not status.get('did_print', False):
+                printer_state = status.get('printer_state', {})
+                status_type = printer_state.get('status_type', 'Unknown')
+                media_type = printer_state.get('media_type', 'Unknown')
+                media_width = printer_state.get('media_width', 'Unknown')
+                errors = printer_state.get('errors', [])
+                
+                error_details = {
+                    "error": f"Print failed: {status_type}",
+                    "status_type": status_type,
+                    "media_type": media_type,
+                    "media_width": media_width,
+                    "errors": errors,
+                    "outcome": status.get('outcome', 'unknown'),
+                    "original_payload": raw_payload
+                }
+                
+                error_msg = f"Print failed: {status_type}. Media: {media_type} ({media_width}mm)"
+                print(error_msg)
+                client.publish(MQTT_TOPIC_PUB_ERRORS, json.dumps(error_details))
+                raise Exception(error_msg)
 
     except json.JSONDecodeError as e:
         error_msg = f"Invalid JSON in message: {e}. Raw payload: {raw_payload}"