Check that pins exist,

make visible when "hide disconnected" is active

src/wireviz/DataClasses.py

@@ -142,7 +142,6 @@ class Connector:
     hide_disconnected_pins: bool = False
     autogenerate: bool = False
     loops: List[List[Pin]] = field(default_factory=list)
-    loop_color: Optional[Color] = "WH"
     ignore_in_bom: bool = False
     additional_components: List[AdditionalComponent] = field(default_factory=list)
 
@@ -179,11 +178,13 @@ class Connector:
             self.show_pincount = self.style != 'simple' # hide pincount for simple (1 pin) connectors by default
 
         for loop in self.loops:
-            # TODO: check that pins to connect actually exist
-            # TODO: allow using pin labels in addition to pin numbers, just like when defining regular connections
-            # TODO: include properties of wire used to create the loop
-            if len(loop) != 2:
-                raise Exception('Loops must be between exactly two pins!')
+            # check that pins to connect actually exist
+            if type(loop) == dict:
+                loop = list(loop.values())[0]
+            for pin in loop:
+                if not ((self.pins.count(pin) == 1) or (self.pinlabels.count == 1)):
+                    raise Exception(f"Didn't find exactly one {self.name}:{pin} to loop into")
+                self.activate_pin(pin)
 
         for i, item in enumerate(self.additional_components):
             if isinstance(item, dict):