patch 8.2.3190: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move error messages to errors.h and give them a clear name.
diff --git a/src/session.c b/src/session.c
index 8edf0da..03b57f0 100644
--- a/src/session.c
+++ b/src/session.c
@@ -977,7 +977,7 @@
 
     if (curbuf->b_ffname == NULL)
     {
-	emsg(_(e_noname));
+	emsg(_(e_no_file_name));
 	return NULL;
     }
     sname = home_replace_save(NULL, curbuf->b_ffname);