pybricksdev.cli.lwp3.repl: fix exception on PortID enum

In Python 3.12, we are getting an exception when trying to cast an int
to a PortID since the enum doesn't have any members.

This can be fixed by adding an unused member.

Fixes: #91

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- Fixed `PortID` exception when running `lwp3 repl` command.
+
 ## [1.0.0-alpha.49] - 2024-06-30
 
 ### Changed

pybricksdev/ble/lwp3/bytecodes.py

@@ -568,6 +568,9 @@ class PortID(IntEnum):
     All enum members are dynamic. (0 to 49 are external and 50 - 100 are internal)
     """
 
+    # not used - Python requires at least one member
+    _PLACEHOLDER = -1
+
     @property
     def internal(self) -> bool:
         """Tests if the port is internal."""
@@ -905,6 +908,9 @@ class HwNetExtFamily(IntEnum):
     a single byte.
     """
 
+    # not used - Python requires at least one member
+    _PLACEHOLDER = -1
+
     @property
     def family(self) -> HwNetFamily:
         return HwNetFamily(self & 0x0F)

pybricksdev/cli/lwp3/repl.py

@@ -84,6 +84,8 @@ def get_completions(self, document: Document, complete_event):
             )
             if cls and issubclass(cls, Enum):
                 for m in cls:
+                    if m.name.startswith("_"):
+                        continue
                     yield Completion(m.name)
         elif document.find_enclosing_bracket_left("(", ")") is not None:
             # if we are inside of "(...)", list the enums and other parameter types