Pthreads & Libcurl - Segmentation Fault when using Authorization header - c++

Question

I have been tearing my hair out for the past 3 days, trying to figure out why my C++ code outputs a "Segmentation fault". Being new to C++ didn't help either. Nor did using pthreads help with narrowing down with the problem (If you aren't able to replicate this, try it with pthreads I guess)
But now, I believe I finally have my fingers on one of the reasons why. Here's the code:
static void* pull_one_url(void* arguments)
{
struct example_struct args = *((struct example_struct *)arguments);
CURL *curl;
curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, ("https://example.com/" + (args).appendData).c_str());
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(curl, CURLOPT_TIMEOUT_MS, 30000L);
// Set Headers
struct curl_slist *header = NULL;
header = curl_slist_append(header, ("Authorization: Bearer " + (args).myBearerToken).c_str());
header = curl_slist_append(header, "User-Agent: MyCPPApp");
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, header);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
CURLcode res = curl_easy_perform(curl);
cout << "Request sent." << endl;
return NULL;
}
Running that code in my case will throw a "Segmentation Error" and crash the app. Using any authorization bearer token seems to do that.
My question is - how do I bypass the segmentation fault? No doubt about it, my app will encounter bad auth tokens and I do NOT want it crashing because of that, especially considering that it's multithreaded and needs to continue it's work.
This may be happening because of the way I'm passing the token down from the casted pthread arguments, but I am at a loss when it comes to finding another way to do it, so if that's the case, kindly show me the right direction.
Oh, and by the way, if you know of a way to safely and easily print the output to the console right after the request in the thread finishes (it's multithreaded, without waiting for all threads to die), then please help me with that too. I am not 100% certain the code I am using right now is safe from these dreaded segmentation faults that seem to be haunting me, so I have excluded it from my testing and this post.