C++: Application crashes with abort() on logging function - c++

Question

here is my code which is run on windows:
Log.h
#include <iostream>
#include <sstream>
#include <fstream>
#include <shared_mutex>
#include <thread>
#include <iomanip>
class Log {
public:
static std::ofstream myfile;
static std::shared_mutex m_smutex;
static bool isLogEnabled();
static void close() {
Log::myfile.close();
}
template< typename... Args >
static void debug(const char* format, Args... args) {
std::unique_lock<std::shared_mutex> lock(Log::m_smutex);
if (isLogEnabled()) {
if (!Log::myfile.is_open()) {
Log::myfile.open("C:\\tmp\\log.txt", std::ios_base::app);
}
...
Log::myfile.close();
}
else {
if (Log::myfile.is_open()) {
Log::myfile.flush();
Log::myfile.close();
}
}
}
};
You can see I've deleted most of the code(...) because I narrowed down the problem.
Log.cpp
#include <Windows.h>
#include "Log.h"
std::ofstream LogLine::myfile;
std::shared_mutex LogLine::m_smutex;
bool LogLine::isLogEnabled() {
CHAR regeditPath[MAX_PATH] = { 0 };
CHAR variable[] = "DEBUG_LOGS";
GetEnvironmentVariableA(variable, regeditPath, MAX_PATH);
return GetLastError() == ERROR_ENVVAR_NOT_FOUND ? false : true;
}
The process needs to be run always, that's why I open and close the file everytime I log something. I want to be able to delete logs even when the process is still running. Maybe this is silly because there might be a flag which would allow me to delete the logs while file is open by some process.
Example usage:
Log::debug("little test %d", 10);
As you can see I use mutex because I want to call debug function from different threads. The problem is that after some time I get error code Abort() has been called but I can't understand why.
P.S
I created this code inside custom Credential Provider to enable debugging, but I'm checking in the internet and it seems like nobody is using logging there. Is it because it's forbidden? Maybe this is reason of the crash?