patch 8.2.1565: spellfile test sometimes fails

Problem:    Spellfile test sometimes fails.
Solution:   Check running into the end of the file.
diff --git a/src/spellfile.c b/src/spellfile.c
index 12dedd6..869db7f 100644
--- a/src/spellfile.c
+++ b/src/spellfile.c
@@ -3533,8 +3533,7 @@
     spin->si_msg_count = 999999;
 
     // Read and ignore the first line: word count.
-    (void)vim_fgets(line, MAXLINELEN, fd);
-    if (!vim_isdigit(*skipwhite(line)))
+    if (vim_fgets(line, MAXLINELEN, fd) || !vim_isdigit(*skipwhite(line)))
 	semsg(_("E760: No word count in %s"), fname);
 
     /*