Handle empty addr2line input

src/symbols/symbols_with_addr2line.cpp

@@ -425,6 +425,13 @@ namespace cpptrace {
                     for(const auto& entry : entries) {
                         const auto& object_name = entry.first;
                         const auto& entries_vec = entry.second;
+                        // You may ask why it'd ever happen that there could be an empty entries_vec array, if there're
+                        // no addresses why would get_addr2line_targets do anything? The reason is because if things in
+                        // get_addr2line_targets fail it will silently skip. This is partly an optimization but also an
+                        // assertion below will fail if addr2line is given an empty input.
+                        if(entries_vec.empty()) {
+                            continue;
+                        }
                         std::string address_input;
                         for(const auto& pair : entries_vec) {
                             address_input += pair.first;