Multiple fixes: signed/unsigned, etc... (#600)

Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>

src/ftxui/component/screen_interactive_test.cpp

@@ -1,6 +1,7 @@
-#include <gtest/gtest.h>
+#include <gtest/gtest.h>  // for Test, TestInfo (ptr only), TEST, EXPECT_EQ, Message, TestPartResult
 #include <csignal>  // for raise, SIGABRT, SIGFPE, SIGILL, SIGINT, SIGSEGV, SIGTERM
 #include <ftxui/component/event.hpp>  // for Event, Event::Custom
+#include <tuple>                      // for _Swallow_assign, ignore
 
 #include "ftxui/component/component.hpp"  // for Renderer
 #include "ftxui/component/screen_interactive.hpp"
@@ -14,7 +15,7 @@ bool TestSignal(int signal) {
   // The tree of components. This defines how to navigate using the keyboard.
   auto component = Renderer([&] {
     called++;
-    std::raise(signal);
+    std::ignore = std::raise(signal);
     called++;
     return text("");
   });