patch 8.2.2598: Vim9: :open does not need to be supported

Problem:    Vim9: :open does not need to be supported.
Solution:   Do not support :open in Vim9 script.
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 40e70c3..c7b57ba 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -6609,6 +6609,10 @@
     regmatch_T	regmatch;
     char_u	*p;
 
+#ifdef FEAT_EVAL
+    if (not_in_vim9(eap) == FAIL)
+	return;
+#endif
     curwin->w_cursor.lnum = eap->line2;
     beginline(BL_SOL | BL_FIX);
     if (*eap->arg == '/')
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index d2f5feb..78ff44b 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -1880,6 +1880,8 @@
   CheckScriptFailure(['vim9script', 'c'], 'E1100:')
   CheckScriptFailure(['vim9script', 'i = 1'], 'E488:')
   CheckScriptFailure(['vim9script', 'i'], 'E1100:')
+  CheckScriptFailure(['vim9script', 'o = 1'], 'E1100:')
+  CheckScriptFailure(['vim9script', 'o'], 'E1100:')
   CheckScriptFailure(['vim9script', 't'], 'E1100:')
   CheckScriptFailure(['vim9script', 't = 1'], 'E1100:')
   CheckScriptFailure(['vim9script', 'x = 1'], 'E1100:')
diff --git a/src/version.c b/src/version.c
index f35f8b0..78eb634 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2598,
+/**/
     2597,
 /**/
     2596,
diff --git a/src/vim9script.c b/src/vim9script.c
index faee131..05977b6 100644
--- a/src/vim9script.c
+++ b/src/vim9script.c
@@ -102,6 +102,7 @@
 	    case CMD_append:
 	    case CMD_change:
 	    case CMD_insert:
+	    case CMD_open:
 	    case CMD_t:
 	    case CMD_xit:
 		semsg(_(e_command_not_supported_in_vim9_script_missing_var_str), eap->cmd);