patch 8.2.4003: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 7f2be49..b76de2d 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -1401,7 +1401,7 @@
     {
 	case ET_USER:
 	    vim_snprintf((char *)IObuff, IOSIZE,
-		    _("E605: Exception not caught: %s"),
+		    _(e_exception_not_caught_str),
 		    current_exception->value);
 	    p = (char *)vim_strsave(IObuff);
 	    break;