Fixed imgui crash

src/main.cpp

@@ -1,6 +1,7 @@
 #include <iostream>
 #include <SFML/Window.hpp>
 #include "input.h"
+#include <imgui/imgui.h>
 
 using namespace std;
 
@@ -29,8 +30,8 @@ int main()
 {
     cerr << "Hello World!"<< endl;
     sf::Window* window= new sf::Window(sf::VideoMode(400,200),"testSparrowInput");
+    ImGui::CreateContext();
     Input myInput(window);
-
     Context context = Context("test",TestKeysMap::getTestContext());
     myInput.setKeysMap(TestKeysMap());
     myInput.addContext(context);