merge our loop which checks for vector rowname extraction in below

Author: Mukulyadav2004

R/as.data.table.R

@@ -133,25 +133,19 @@ as.data.table.list = function(x,
   missing.check.names = missing(check.names)
   origListNames = if (missing(.named)) names(x) else NULL  # as.data.table called directly, not from inside data.table() which provides .named, #3854
   empty_atomic = FALSE
-
-  #Handle keep.rownames for vectors (mimicking data.frame behavior)
+  # Handle keep.rownames for vectors (mimicking data.frame behavior)
   vector_rownames = NULL
-  if (!isFALSE(keep.rownames)) {
-    for (i in seq_len(n)) {
-      xi = x[[i]]
-      if (!is.null(xi) && is.atomic(xi) && !is.null(names(xi)) && is.null(dim(xi))) {
-        valid_names = names(xi)
-        if (any(nzchar(valid_names))) {
-          vector_rownames = valid_names
-          x[[i]] = unname(xi)
-          break
-        }
-      }
-    }
-  }
+  check_rownames = !isFALSE(keep.rownames)
   for (i in seq_len(n)) {
     xi = x[[i]]
     if (is.null(xi)) next    # eachncol already initialized to 0 by integer() above
+    if (check_rownames && is.null(vector_rownames) && !is.null(xi) && is.atomic(xi) && !is.null(names(xi)) && is.null(dim(xi))) {
+      valid_names = names(xi)
+      if (any(nzchar(valid_names))) {
+        vector_rownames = valid_names
+        x[[i]] = unname(xi)
+      }
+    }
     if (!is.null(dim(xi)) && missing.check.names) check.names=TRUE
     if ("POSIXlt" %chin% class(xi)) {
       warningf("POSIXlt column type detected and converted to POSIXct. We do not recommend use of POSIXlt at all because it uses 40 bytes to store one date.")