patch 8.2.3970: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more errors to errors.h.
diff --git a/src/if_xcmdsrv.c b/src/if_xcmdsrv.c
index 763eee5..25f63de 100644
--- a/src/if_xcmdsrv.c
+++ b/src/if_xcmdsrv.c
@@ -1323,7 +1323,7 @@
 			    ga_concat(&reply, res);
 			else
 			{
-			    ga_concat(&reply, (char_u *)_(e_invexprmsg));
+			    ga_concat(&reply, (char_u *)_(e_invalid_expression_received));
 			    ga_append(&reply, 0);
 			    ga_concat(&reply, (char_u *)"-c 1");
 			}