patch 8.2.3975: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/gui.c b/src/gui.c
index a5f449a..292da7c 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -547,7 +547,7 @@
 	    if (STRCMP(use_gvimrc, "NONE") != 0
 		    && STRCMP(use_gvimrc, "NORC") != 0
 		    && do_source(use_gvimrc, FALSE, DOSO_NONE, NULL) != OK)
-		semsg(_("E230: Cannot read from \"%s\""), use_gvimrc);
+		semsg(_(e_cannot_read_from_str), use_gvimrc);
 	}
 	else
 	{
@@ -686,7 +686,7 @@
 	goto error2;
     }
     if (gui_get_wide_font() == FAIL)
-	emsg(_("E231: 'guifontwide' invalid"));
+	emsg(_(e_guifontwide_invalid));
 
     gui.num_cols = Columns;
     gui.num_rows = Rows;