patch 8.2.4010: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/undo.c b/src/undo.c
index 40f97b1..4c02551 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -784,8 +784,6 @@
 // extra fields for uhp
 # define UHP_SAVE_NR		1
 
-static char_u e_not_open[] = N_("E828: Cannot open undo file for writing: %s");
-
 /*
  * Compute the hash for the current buffer text into hash[UNDO_HASH_SIZE].
  */
@@ -898,7 +896,7 @@
     static void
 corruption_error(char *mesg, char_u *file_name)
 {
-    semsg(_("E825: Corrupted undo file (%s): %s"), mesg, file_name);
+    semsg(_(e_corrupted_undo_file_str_str), mesg, file_name);
 }
 
     static void
@@ -1680,7 +1678,7 @@
 			    O_CREAT|O_EXTRA|O_WRONLY|O_EXCL|O_NOFOLLOW, perm);
     if (fd < 0)
     {
-	semsg(_(e_not_open), file_name);
+	semsg(_(e_cannot_open_undo_file_for_writing_str), file_name);
 	goto theend;
     }
     (void)mch_setperm(file_name, perm);
@@ -1719,7 +1717,7 @@
     fp = fdopen(fd, "w");
     if (fp == NULL)
     {
-	semsg(_(e_not_open), file_name);
+	semsg(_(e_cannot_open_undo_file_for_writing_str), file_name);
 	close(fd);
 	mch_remove(file_name);
 	goto theend;
@@ -1792,7 +1790,7 @@
 write_error:
     fclose(fp);
     if (!write_ok)
-	semsg(_("E829: write error in undo file: %s"), file_name);
+	semsg(_(e_write_error_in_undo_file_str), file_name);
 
 #if defined(MSWIN)
     // Copy file attributes; for systems where this can only be done after
@@ -1904,7 +1902,7 @@
     if (fp == NULL)
     {
 	if (name != NULL || p_verbose > 0)
-	    semsg(_("E822: Cannot open undo file for reading: %s"), file_name);
+	    semsg(_(e_cannot_open_undo_file_for_reading_str), file_name);
 	goto error;
     }
     bi.bi_buf = curbuf;
@@ -1916,7 +1914,7 @@
     if (fread(magic_buf, UF_START_MAGIC_LEN, 1, fp) != 1
 		|| memcmp(magic_buf, UF_START_MAGIC, UF_START_MAGIC_LEN) != 0)
     {
-	semsg(_("E823: Not an undo file: %s"), file_name);
+	semsg(_(e_not_an_undo_file_str), file_name);
 	goto error;
     }
     version = get2c(fp);
@@ -1925,14 +1923,13 @@
 #ifdef FEAT_CRYPT
 	if (*curbuf->b_p_key == NUL)
 	{
-	    semsg(_("E832: Non-encrypted file has encrypted undo file: %s"),
-								   file_name);
+	    semsg(_(e_non_encrypted_file_has_encrypted_undo_file), file_name);
 	    goto error;
 	}
 	bi.bi_state = crypt_create_from_file(fp, curbuf->b_p_key);
 	if (bi.bi_state == NULL)
 	{
-	    semsg(_("E826: Undo file decryption failed: %s"), file_name);
+	    semsg(_(e_undo_file_decryption_failed), file_name);
 	    goto error;
 	}
 	if (crypt_whole_undofile(bi.bi_state->method_nr))
@@ -1948,13 +1945,13 @@
 	    bi.bi_used = 0;
 	}
 #else
-	semsg(_("E827: Undo file is encrypted: %s"), file_name);
+	semsg(_(e_undo_file_is_encrypted_str), file_name);
 	goto error;
 #endif
     }
     else if (version != UF_VERSION)
     {
-	semsg(_("E824: Incompatible undo file: %s"), file_name);
+	semsg(_(e_incompatible_undo_file_str), file_name);
 	goto error;
     }
 
@@ -2522,7 +2519,7 @@
 
 	if (absolute)
 	{
-	    semsg(_("E830: Undo number %ld not found"), step);
+	    semsg(_(e_undo_number_nr_not_found), step);
 	    return;
 	}