Fix crash on Linux when using unmapped keyboard Keyboard

#1321

Source/Engine/Input/Input.cpp

@@ -333,6 +333,8 @@ void Keyboard::OnCharInput(Char c, Window* target)
 
 void Keyboard::OnKeyUp(KeyboardKeys key, Window* target)
 {
+    if (key >= KeyboardKeys::MAX)
+        return;
     Event& e = _queue.AddOne();
     e.Type = EventType::KeyUp;
     e.Target = target;
@@ -341,6 +343,8 @@ void Keyboard::OnKeyUp(KeyboardKeys key, Window* target)
 
 void Keyboard::OnKeyDown(KeyboardKeys key, Window* target)
 {
+    if (key >= KeyboardKeys::MAX)
+        return;
     Event& e = _queue.AddOne();
     e.Type = EventType::KeyDown;
     e.Target = target;

Source/Engine/Platform/Linux/LinuxPlatform.cpp

@@ -2206,6 +2206,10 @@ bool LinuxPlatform::Init()
 				KeyCodeMap[keyCode] = key;
 			}
 		}
+        else
+        {
+			KeyCodeMap[keyCode] = KeyboardKeys::None;
+        }
 	}
 
     Input::Mouse = Impl::Mouse = New<LinuxMouse>();