values: Don't allow assigning true/false to object

Fix a bug in the type checking code where it would not produce an error
if you assigned "true" or "false" to an object property.

blueprintcompiler/language/values.py

@@ -338,7 +338,14 @@ class IdentLiteral(AstNode):
                         raise CompileError(
                             '"item" can only be used in an expression literal'
                         )
-                elif self.ident not in ["true", "false"]:
+                elif self.ident in ["true", "false"]:
+                    if expected_type is not None and not isinstance(
+                        expected_type, gir.BoolType
+                    ):
+                        raise CompileError(
+                            f"Cannot assign boolean to {expected_type.full_name}"
+                        )
+                else:
                     raise CompileError(
                         f"Could not find object with ID {self.ident}",
                         did_you_mean=(

tests/sample_errors/convert_bool_to_obj.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+Button {
+  child: false;
+}

tests/sample_errors/convert_bool_to_obj.err

@@ -0,0 +1 @@
+4,10,5,Cannot assign boolean to Gtk.Widget