prevent use-after-free.

Common/LogManager.cpp

@@ -176,6 +176,7 @@ void LogManager::ChangeFileLog(const char *filename) {
 	if (fileLog_) {
 		RemoveListener(fileLog_);
 		delete fileLog_;
+		fileLog_ = nullptr;
 	}
 
 	if (filename) {

GPU/Vulkan/TextureCacheVulkan.cpp

@@ -182,7 +182,11 @@ void TextureCacheVulkan::DeviceLost() {
 	}
 
 	samplerCache_.DeviceLost();
-	vulkan_->Delete().QueueDeleteSampler(samplerNearest_);
+
+	if(samplerNearest_) {
+		vulkan_->Delete().QueueDeleteSampler(samplerNearest_);
+		samplerNearest_ = VK_NULL_HANDLE;
+	}
 
 	nextTexture_ = nullptr;
 }