Fix mypy errors.

gso/products/product_blocks/layer_2_circuit.py

 """Layer 2 Circuit product block."""
 
+from collections.abc import Sequence
 from typing import Annotated, TypeVar
 
 from annotated_types import Len
@@ -51,7 +52,7 @@ Layer2CircuitSideBlockType = TypeVar(
 )
 
 Layer2CircuitSides = Annotated[
-    list[Layer2CircuitSideBlockType],
+    Sequence[Layer2CircuitSideBlockType],
     AfterValidator(validate_unique_list),
     Len(min_length=2, max_length=2),
     Doc("A list of two Layer 2 Circuit sides."),

gso/workflows/l2_circuit/create_layer_2_circuit.py

@@ -52,12 +52,6 @@ def initial_input_generator(product_name: str) -> FormGenerator:
     class Layer2CircuitServiceSidesPage(FormPage):
         model_config = ConfigDict(title=f"{product_name} - Configure Edge Ports")
 
-        vlan_range_label: Label | None = Field(None, exclude=True)
-        vlan_range_lower_bound: VLAN_ID | None = None
-        vlan_range_upper_bound: VLAN_ID | None = None
-
-        policer_bandwidth: BandwidthString | None = None
-
         if initial_user_input.layer_2_circuit_type == Layer2CircuitType.TAGGED:
             vlan_range_label: Label = Field("Please set a VLAN range, bounds including.", exclude=True)
             vlan_range_lower_bound: VLAN_ID
@@ -79,6 +73,22 @@ def initial_input_generator(product_name: str) -> FormGenerator:
         side_divider: Divider = Field(None, exclude=True)
         layer_2_circuit_side_b: Layer2CircuitSideSelection
 
+        def __init__(self, **data: Any):
+            """Initialize fields based on user input conditions."""
+            super().__init__(**data)
+            if initial_user_input.layer_2_circuit_type == Layer2CircuitType.TAGGED:
+                self.vlan_range_label = Field("Please set a VLAN range, bounds including.", exclude=True)
+                self.vlan_range_lower_bound = VLAN_ID()
+                self.vlan_range_upper_bound = VLAN_ID()
+            else:
+                self.vlan_range_lower_bound = ReadOnlyField(None, default_type=int)
+                self.vlan_range_upper_bound = ReadOnlyField(None, default_type=int)
+
+            if initial_user_input.policer_enabled:
+                self.policer_bandwidth = BandwidthString()
+            else:
+                self.policer_bandwidth = ReadOnlyField(None, default_type=int)
+
     layer_2_circuit_input = yield Layer2CircuitServiceSidesPage
 
     return {"product_name": product_name} | initial_user_input.model_dump() | layer_2_circuit_input.model_dump()