Fix bug on pre-build const connection extraction

lib/src/connection_extractor.dart

@@ -183,14 +183,22 @@ class _ConnectionSliceTracking {
   final List<int> dstDimensionAccess;
 
   /// The module of the [src].
-  BridgeModule get srcModule => src.parentModule! as BridgeModule;
+  BridgeModule get srcModule => (src is Const && src.parentModule == null)
+      ? throw RohdBridgeException('Const has no parent module pre-build.')
+      : src.parentModule! as BridgeModule;
 
   /// The module of the [dst].
   BridgeModule get dstModule => dst.parentModule! as BridgeModule;
 
   /// Converts the [src] to a [PortReference].
   Reference toSrcRef() => src is Const
-      ? ConstReference(src.value, module: srcModule)
+      ? ConstReference(
+          src.value,
+
+          // use the `dstModule` since we haven't necessarily built yet and the
+          // source is a `Const`, not a port
+          module: dstModule,
+        )
       : PortReference.fromPort(src).slice(srcHighIndex, srcLowIndex);
 
   /// Converts the [dst] to a [PortReference].

test/connection_extractor_test.dart

@@ -1111,4 +1111,36 @@ void main() {
             .value,
         LogicValue.ofString('11'));
   });
+
+  test('connection extraction with consts pre-build', () {
+    final top = BridgeModule('top');
+    final subMod = BridgeModule('subMod');
+    final myDst = subMod.createPort('myDst', PortDirection.input, width: 8);
+    top.addSubModule(subMod);
+
+    myDst.slice(4, 3).tieOff(value: 3);
+    top.pullUpPort(myDst.slice(6, 5));
+
+    final extractor = ConnectionExtractor([top, subMod]);
+
+    final connections = extractor.connections;
+    expect(connections.whereType<TieOffConnection>().length, 2);
+
+    expect(connections.whereType<TieOffConnection>().first.src.module, subMod);
+
+    expect(
+        connections
+            .whereType<TieOffConnection>()
+            .firstWhere((e) => e.dst.toString().contains('myDst[3]'))
+            .src
+            .value,
+        LogicValue.ofString('11'));
+    expect(
+        connections
+            .whereType<TieOffConnection>()
+            .firstWhere((e) => e.dst.toString().contains('myDst[4]'))
+            .src
+            .value,
+        LogicValue.ofString('11'));
+  });
 }