Fix for #13255: Check if client has a block even if the server has un…

…loaded it. (#13256)

src/clientiface.cpp

@@ -298,18 +298,19 @@ void RemoteClient::GetNextBlocks (
 				Check if map has this block
 			*/
 			MapBlock *block = env->getMap().getBlockNoCreateNoEx(p);
-
-			bool block_not_found = false;
 			if (block) {
-				// Reset usage timer, this block will be of use in the future.
+				// First: Reset usage timer, this block will be of use in the future.
 				block->resetUsageTimer();
+			}
 
-				/*
-					Don't send already sent blocks
-				*/
-				if (m_blocks_sent.find(p) != m_blocks_sent.end())
-					continue;
+			/*
+				Don't send already sent blocks
+			*/
+			if (m_blocks_sent.find(p) != m_blocks_sent.end())
+				continue;
 
+			bool block_not_found = false;
+			if (block) {
 				// Check whether the block exists (with data)
 				if (!block->isGenerated())
 					block_not_found = true;