autoconnect only if there is exactly one device

Signed-off-by: Martin <Ho-Ro@users.noreply.github.com>

src/NanoVNASaver/NanoVNASaver.py

@@ -473,8 +473,8 @@ class NanoVNASaver(QWidget):
 
         logger.debug("Finished building interface")
 
-    def auto_connect( self ): # connect to the 1st detected serial device
-        if self.serial_control.inp_port.currentData():
+    def auto_connect( self ): # connect if there is exactly one detected serial device
+        if self.serial_control.inp_port.count() == 1:
             self.serial_control.connect_device()
 
     def _sweep_control(self, start: bool = True) -> None:

src/NanoVNASaver/__main__.py

@@ -47,7 +47,7 @@ def main():
         "-D", "--debug-file", help="File to write debug logging output to"
     )
     parser.add_argument(
-        "-a", "--auto-connect", action="store_true", help="Auto connect to detected 1st device"
+        "-a", "--auto-connect", action="store_true", help="Auto connect if one device detected"
     )
     parser.add_argument(
         "-f",