patch 8.2.3967: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more errors to errors.h.
diff --git a/src/getchar.c b/src/getchar.c
index 704d4d3..d9b55c0 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -1467,7 +1467,7 @@
     expand_env(name, NameBuff, MAXPATHL);
     if ((scriptin[curscript] = mch_fopen((char *)NameBuff, READBIN)) == NULL)
     {
-	semsg(_(e_notopen), name);
+	semsg(_(e_cant_open_file_str), name);
 	if (curscript)
 	    --curscript;
 	return;