Prevent stacktrace from being shown in case of no devices

Author: Tomer Shalev

src/labelle/cli/cli.py

@@ -28,7 +28,7 @@
     Justify,
     e_qrcode,
 )
-from labelle.lib.devices.device_manager import DeviceManager, DeviceManagerError
+from labelle.lib.devices.device_manager import DeviceManager, DeviceManagerNoDevices
 from labelle.lib.devices.dymo_labeler import DymoLabeler
 from labelle.lib.env_config import is_verbose_env_vars
 from labelle.lib.font_config import NoFontFound, get_available_fonts, get_font_path
@@ -89,18 +89,23 @@ def qr_callback(qr_content: str) -> str:
     return qr_content
 
 
-app = typer.Typer()
-
-
-@app.command()
-def list_devices():
+def get_device_manager() -> DeviceManager:
     device_manager = DeviceManager()
     try:
         device_manager.scan()
-    except DeviceManagerError as e:
-        typer.echo(e)
+    except DeviceManagerNoDevices as e:
+        err_console = Console(stderr=True)
+        err_console.print(f"Error: {e}")
         raise typer.Exit() from e
+    return device_manager
+
 
+app = typer.Typer()
+
+
+@app.command()
+def list_devices():
+    device_manager = get_device_manager()
     console = Console()
     table = Table(show_header=True)
     table.add_column("Manufacturer")
@@ -296,8 +301,7 @@ def default(
     )
 
     if output == Output.printer:
-        device_manager = DeviceManager()
-        device_manager.scan()
+        device_manager = get_device_manager()
         device = device_manager.find_and_select_device(patterns=device_pattern)
         device.setup()
     else:

src/labelle/lib/devices/device_manager.py

@@ -18,6 +18,10 @@ class DeviceManagerError(RuntimeError):
     pass
 
 
+class DeviceManagerNoDevices(DeviceManagerError):
+    pass
+
+
 class DeviceManager:
     _devices: dict[str, UsbDevice]
 
@@ -33,7 +37,7 @@ def scan(self) -> bool:
             raise DeviceManagerError(f"Failed scanning devices: {e}") from e
         if len(cur) == 0:
             self._devices.clear()
-            raise DeviceManagerError("No supported devices found")
+            raise DeviceManagerNoDevices("No supported devices found")
 
         prev_set = set(prev)
         cur_set = set(cur)