XCI: Add function for checking the existence of the program NCA

The only reason the getter existed was to check whether or not the
program NCA was null. Instead, we can just provide a function to query
for the existence of it, instead of exposing it entirely.

src/core/file_sys/card_image.cpp

@@ -122,14 +122,16 @@ u64 XCI::GetProgramTitleID() const {
     return secure_partition->GetProgramTitleID();
 }
 
-std::shared_ptr<NCA> XCI::GetProgramNCA() const {
-    return program;
+bool XCI::HasProgramNCA() const {
+    return program != nullptr;
 }
 
 VirtualFile XCI::GetProgramNCAFile() const {
-    if (GetProgramNCA() == nullptr)
+    if (!HasProgramNCA()) {
         return nullptr;
-    return GetProgramNCA()->GetBaseFile();
+    }
+
+    return program->GetBaseFile();
 }
 
 const std::vector<std::shared_ptr<NCA>>& XCI::GetNCAs() const {

src/core/file_sys/card_image.h

@@ -80,7 +80,7 @@ public:
 
     u64 GetProgramTitleID() const;
 
-    std::shared_ptr<NCA> GetProgramNCA() const;
+    bool HasProgramNCA() const;
     VirtualFile GetProgramNCAFile() const;
     const std::vector<std::shared_ptr<NCA>>& GetNCAs() const;
     std::shared_ptr<NCA> GetNCAByType(NCAContentType type) const;

src/core/loader/xci.cpp

@@ -59,8 +59,7 @@ ResultStatus AppLoader_XCI::Load(Kernel::Process& process) {
     if (xci->GetProgramNCAStatus() != ResultStatus::Success)
         return xci->GetProgramNCAStatus();
 
-    const auto nca = xci->GetProgramNCA();
-    if (nca == nullptr && !Core::Crypto::KeyManager::KeyFileExists(false))
+    if (!xci->HasProgramNCA() && !Core::Crypto::KeyManager::KeyFileExists(false))
         return ResultStatus::ErrorMissingProductionKeyFile;
 
     const auto result = nca_loader->Load(process);