DITConfiguration: Prevent a crash if images fail to load

Recently came across a strange issue where Dolphin would hard crash in most games with this error:

```sh
/usr/include/c++/15.2.1/optional:1165: constexpr const _Tp* std::optional<_Tp>::operator->() const [with _Tp = InputCommon::ImagePixelData]: Assertion 'this->_M_is_engaged()' failed.
```

The culprit turned out to be accessing `host_key_image` which is an `std::optional` thay may return `std::nullopt`. I'm not sure why this issue started occuring for me since I've had no issue with my Dynamic Input Textures in the past? But this fixes a crash if the image fails to load.

1 files changed, 5 insertions, 2 deletions

diff --git a/Source/Core/InputCommon/ImageOperations.cpp b/Source/Core/InputCommon/ImageOperations.cpp
index 907cb52b8d..8fa844fec1 100644
--- a/Source/Core/InputCommon/ImageOperations.cpp
+++ b/Source/Core/InputCommon/ImageOperations.cpp
@@ -45,9 +45,12 @@ void CopyImageRegion(const ImagePixelData& src, ImagePixelData& dst, const Rect&
 std::optional<ImagePixelData> LoadImage(const std::string& path)
 {
   File::IOFile file;
-  file.Open(path, "rb");
+  if (!file.Open(path, "rb"))
+    return std::nullopt;
+
   Common::UniqueBuffer<u8> buffer(file.GetSize());
-  file.ReadBytes(buffer.data(), file.GetSize());
+  if (!file.ReadBytes(buffer.data(), file.GetSize()))
+    return std::nullopt;
 
   ImagePixelData image;
   Common::UniqueBuffer<u8> data;