lib/model: Improve errors while pulling (#5474)

lib/model/folder_sendrecv.go

@@ -64,7 +64,7 @@ var (
 	errSymlinksUnsupported = errors.New("symlinks not supported")
 	errDirHasToBeScanned   = errors.New("directory contains unexpected files, scheduling scan")
 	errDirHasIgnored       = errors.New("directory contains ignored files (see ignore documentation for (?d) prefix)")
-	errDirNotEmpty         = errors.New("directory is not empty")
+	errDirNotEmpty         = errors.New("directory is not empty; files within are probably ignored on connected devices only")
 	errNotAvailable        = errors.New("no connected device has the required version of this file")
 	errModified            = errors.New("file modified but not rescanned; will try again later")
 )
@@ -1397,7 +1397,8 @@ func (f *sendReceiveFolder) pullBlock(state pullBlockState, out chan<- *sharedPu
 		// Fetch the block, while marking the selected device as in use so that
 		// leastBusy can select another device when someone else asks.
 		activity.using(selected)
-		buf, lastError := f.model.requestGlobal(selected.ID, f.folderID, state.file.Name, state.block.Offset, int(state.block.Size), state.block.Hash, state.block.WeakHash, selected.FromTemporary)
+		var buf []byte
+		buf, lastError = f.model.requestGlobal(selected.ID, f.folderID, state.file.Name, state.block.Offset, int(state.block.Size), state.block.Hash, state.block.WeakHash, selected.FromTemporary)
 		activity.done(selected)
 		if lastError != nil {
 			l.Debugln("request:", f.folderID, state.file.Name, state.block.Offset, state.block.Size, "returned error:", lastError)