bug: Combo-box in device settings has only 101 option for valid sweep points for NanoVNA-F_V2

[superduty]

Bug Report

NanoVNA-Saver version:
0.7.3 Windows 10

Current behavior:
After connecting to Com port _F_V2 and selecting "Manage" to set sweep points, only selection is "101". Upon running with debug option, I can see "variable not iterable "error:

Expected behavior:

Combo-box should have all the points options as per the source code in NanoVNA_F_V2.

Steps to reproduce:
Select manage with device NanoVNA-F-V2 from Sysjoint connected, using -d option to get error above. I can only test in windows 10 currently.

Related code:

Traceback (most recent call last):
File "C:\Users\john\Desktop\vna\nanovna-saver\src\NanoVNASaver\Controls\SerialControl.py", line 70, in
lambda: self.app.display_window("device_settings")
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\john\Desktop\vna\nanovna-saver\src\NanoVNASaver\NanoVNASaver.py", line 640, in display_window
self.windows[name].show()
File "C:\Users\john\Desktop\vna\nanovna-saver\src\NanoVNASaver\Windows\DeviceSettings.py", line 145, in show
self.updateFields()
File "C:\Users\john\Desktop\vna\nanovna-saver\src\NanoVNASaver\Windows\DeviceSettings.py", line 171, in updateFields
for item in features:
^^^^^^^^
TypeError: 'NoneType' object is not iterable

Code from GitHub:

class NanoVNA_F_V2(NanoVNA):
    name = "NanoVNA-F_V2"
    screenwidth = 800
    screenheight = 480
    valid_datapoints: tuple[int, ...] = (101, 11, 51, 201, 301)
    sweep_points_min = 11
    sweep_points_max = 301

Other information:
My device is a Sysjoint NanoVNA-F_V2 with firmware 0.5.4

I debugged the error by cloning to my PC locally. It appears that the issue is simply a missing return statement at the end of the Hardware/NanoVNA_F_V2.py, get_features function.

Code:
def get_features(self):
super().get_features()
result = " ".join(self.exec_command("help")).split()
if "sn:" or "SN:" in result:
self.features.add("SN")
self.SN = self.getSerialNumber()
****************should have "return self.features" here ****************
def getSerialNumber(self) -> str: I can edit the module adding "return self.features" at the end and re-building.

I probably should do a pull request and push the fix, but I am just learning the "GIT" environment and haven't yet done that "official" process.

I struggled with the build process for Windows but eventually stumbled accross the instructions for using "uv"!

As a side issue, I keep seeing that with 0.5.4 firmware its supposed to handle 301 sweep points and that is what is currently shown in the software. However, my unit seems to time-out whet I set it to 301. Works fine at 201.

Thanks to everyone who has contributed to the excellent software package!