Store MultiPackageCache using a reference

Signed-off-by: Julien Jerphanion <git@jjerphan.xyz>

Author: jjerphan

libmamba/include/mamba/core/package_fetcher.hpp

@@ -116,7 +116,7 @@ namespace mamba
         void update_monitor(progress_callback_t* cb, PackageExtractEvent event) const;
 
         specs::PackageInfo m_package_info;
-        MultiPackageCache* m_caches = nullptr;
+        MultiPackageCache& m_caches;
 
         fs::u8path m_tarball_path;
         fs::u8path m_cache_path;

libmamba/src/core/package_fetcher.cpp

@@ -139,7 +139,7 @@ namespace mamba
 
     PackageFetcher::PackageFetcher(const specs::PackageInfo& pkg_info, MultiPackageCache& caches)
         : m_package_info(pkg_info)
-        , m_caches(&caches)
+        , m_caches(caches)
     {
         const fs::u8path extracted_cache = caches.get_extracted_dir_path(m_package_info);
         if (extracted_cache.empty())
@@ -360,7 +360,7 @@ namespace mamba
                 LOG_DEBUG << "Extracted to '" << extract_path.string() << "'";
                 write_repodata_record(extract_path);
                 update_urls_txt();
-                m_caches->clear_query_cache(m_package_info);
+                m_caches.clear_query_cache(m_package_info);
                 update_monitor(cb, PackageExtractEvent::extract_success);
             }
             catch (const std::logic_error&)