Function EXPECTED_TRY

lib/loader/ast/section.cpp:104–107

    return loadSectionContentVec(
        Sec, [this](uint32_t &FuncIdx) -> Expect<void> {
          EXPECTED_TRY(uint32_t Idx, FMgr.readU32().map_error([this](auto E) {
            return logLoadError(E, FMgr.getLastOffset(),
                                ASTNodeAttr::Sec_Function);
          }));
          FuncIdx = Idx;
          return {};
        });