Fix typo, idiomatic empty check, and missing nullptr arg in converter_lib.cpp

Agent-Logs-Url: https://github.com/Cpp2Rust/cpp2rust/sessions/b040cd89-3c59-4900-bde6-77258f6721f9

Co-authored-by: nunoplopes <2998477+nunoplopes@users.noreply.github.com>

Author: Copilot

cpp2rust/converter/converter_lib.cpp

@@ -274,8 +274,8 @@ GetUserDefinedDefaultConstructor(const clang::CXXRecordDecl *decl) {
 
 std::string GetMainFileName(const clang::ASTContext &ctx) {
   const auto &src_mgr = ctx.getSourceManager();
-  auto filed_id = src_mgr.getMainFileID();
-  auto file_entry = src_mgr.getFileEntryRefForID(filed_id);
+  auto file_id = src_mgr.getMainFileID();
+  auto file_entry = src_mgr.getFileEntryRefForID(file_id);
   auto file_path = file_entry->getName();
   auto file_name = llvm::sys::path::filename(file_path);
   return llvm::sys::path::stem(file_name).str();
@@ -399,7 +399,7 @@ std::string GetNamedDeclAsString(const clang::NamedDecl *decl) {
     }
   }
 
-  if (name.size() == 0) {
+  if (name.empty()) {
     name = "self";
   }
 
@@ -539,7 +539,7 @@ GetTemplateArgs(clang::QualType qual_type, clang::Expr *expr) {
   if (auto pt = qual_type->getPointeeType(); !pt.isNull())
     qual_type = pt;
 
-  return GetTemplateArgs(qual_type);
+  return GetTemplateArgs(qual_type, nullptr);
 }
 
 clang::Expr *GetCallObject(clang::CallExpr *expr) {