fix(visitor): handle missing import cases in DWARF visitor

Fix #5

Author: wu-vincent

src/dwarf2cpp/filters.py

@@ -61,7 +61,6 @@ def do_insert_name(tp: str, name: str):
         t,
     )
     if m:
-        print(t)
         ret = m.group("ret").strip()
         cls = m.group("cls").strip()
         args = m.group("args").strip()

src/dwarf2cpp/visitor.py

@@ -532,12 +532,17 @@ def visit_imported_declaration(self, die: DWARFDie) -> None:
 
         import_die = die.find("DW_AT_import").as_referenced_die()
         self.visit(import_die)
+        if import_die.offset not in self._cache:
+            return
+
         if import_die.tag == "DW_TAG_namespace":
             import_ = self._cache[import_die.offset]
             imported_decl = ImportedDeclaration(name=die.short_name, import_=import_)
         else:
             imported_decl = ImportedDeclaration(name="", import_=get_qualified_type(import_die))
 
+        assert imported_decl.import_ is not None, "Expected valid import."
+
         for attribute in die.attributes:
             if attribute.name in {
                 "DW_AT_decl_file",