Assertion '!empty()' failed

[ast261]

Application crashes. Steps to reproduce:

• initial start
• On the web page open tab "Log"
• in HttpServer::methodGet file = "log.json"
• in base::JSONSerializer::checkAddComma string _json is empty
• _json.back() is crashing ("Assertion '!empty()' failed."):
  std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::reference std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::back() [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; reference = char&]: Assertion '!empty()' failed.

[ast261]

Possible fix:

diff --git a/src/base/JSONSerializer.h b/src/base/JSONSerializer.h
index 5c88ca3..1bacce7 100644
--- a/src/base/JSONSerializer.h
+++ b/src/base/JSONSerializer.h
@@ -100,10 +100,12 @@ namespace base {
                private:
 
                        void checkAddComma() {
-                               const char c = _json.back();
-                               if (c == '\"' || c == '}' || c == ']' || std::isdigit(c)) {
-                                       _json += ", ";
-                               }
+                if(!_json.empty()) {
+                    const char c = _json.back();
+                    if (c == '\"' || c == '}' || c == ']' || std::isdigit(c)) {
+                        _json += ", ";
+                    }
+                }
                        }
 
                        std::string makeJSONString(const std::string &msg) {