fix: 🐛 Fix nonetype error throwing from pcbnew.ToMils (#7)

* fix: 🐛 Fix nonetype error throwing from pcbnew.ToMils

Check if the param from design setting is None before converting it

* feat: Update the gif path in the README

README.md

@@ -9,7 +9,7 @@ HQ NextPCB's Active manufacturing plugin will help you:
 - Generate Gerber files and upload them to NextPCB along with your personal board settings
 
 Once the upload is complete, you can use the HQDFM Gerber Viewer to double check your manufacturing files, adjust board parameters then add it to your NextPCB cart directly.
-![NextPCB Plugin](https://github.com/HubertHQH/HQ-NextPCB/assets/125419974/b7002006-7fc4-4a02-be14-cd5ab3bb0774)
+![NextPCB Plugin](https://github.com/SYSUeric66/kicad-amf-plugin/blob/8318782634b7f8237bd4a650c37e4031e876e3a0/docs/amf.gif)
 
 ## Features
 

kicad_amf_plugin/pcb_fabrication/process/process_info_view.py

@@ -301,7 +301,13 @@ def setup_trace_and_via(self):
                     continue
                 minHoleSize = min(minHoleSize, i.GetDrillValue())
 
+        if minTraceWidth is None:
+            minTraceWidth = 0
+        if minTraceClearance is None:
+            minTraceClearance = 0
         self.set_min_trace(
             pcbnew.ToMils(minTraceWidth), pcbnew.ToMils(minTraceClearance)
         )
+        if minHoleSize is None:
+            minHoleSize = 0
         self.set_min_hole(pcbnew.ToMM(minHoleSize))