log: Do not assume the TERM variable is always set

libavutil/log.c

@@ -74,7 +74,7 @@ static void check_color_terminal(void)
     char *term = getenv("TERM");
     use_color = !getenv("NO_COLOR") && !getenv("AV_LOG_FORCE_NOCOLOR") &&
                 (getenv("TERM") && isatty(2) || getenv("AV_LOG_FORCE_COLOR"));
-    use_color += !!strstr(term, "256color") ;
+    use_color += term && strstr(term, "256color");
 #else
     use_color = getenv("AV_LOG_FORCE_COLOR") && !getenv("NO_COLOR") &&
                !getenv("AV_LOG_FORCE_NOCOLOR");