avoid crash on empty branches

CMakeLists.txt

@@ -35,8 +35,6 @@ include(CheckIncludeFiles)
 include(CheckLibraryExists)
 include(CMakePackageConfigHelpers)
 include(CheckCXXSourceCompiles)
-
-# include(Dart)
 include(AddGitSubmodule)
 
 set(CXX_EXTENSIONS OFF)

src/model.cpp

@@ -1133,6 +1133,8 @@ branch::branch(structure &structure, const std::string &asym_id)
 
 void branch::link_atoms()
 {
+	if (not empty())
+	{
 		using namespace literals;
 
 		auto &db = m_structure->get_datablock();
@@ -1151,6 +1153,7 @@ void branch::link_atoms()
 
 			s1.set_link(s2.get_atom_by_atom_id(atom2));
 		}
+	}
 }
 
 std::string branch::name() const
@@ -1375,6 +1378,9 @@ void structure::load_data()
 		ri->second->add_atom(atom);
 	}
 
+	// what the ...
+	m_branches.erase(std::remove_if(m_branches.begin(), m_branches.end(), [](const branch &b) { return b.empty(); }), m_branches.end());
+
 	for (auto &branch : m_branches)
 		branch.link_atoms();
 }