patch 8.2.4835: Vim9: some lines not covered by tests

Problem:    Vim9: some lines not covered by tests.
Solution:   Add a few more tests.  Fix disassemble output.

src/testdir/test_vim9_cmd.vim

@@ -1691,6 +1691,9 @@ def Test_substitute_expr()
   endfor
   assert_equal('yes no abc', getline(1))
 
+  setline(1, 'from')
+  v9.CheckDefExecFailure(['s/from/\=g:notexist/'], 'E121: Undefined variable: g:notexist')
+
   bwipe!
 
   v9.CheckDefFailure(['s/from/\="x")/'], 'E488:')

src/testdir/test_vim9_disassemble.vim

@@ -899,6 +899,25 @@ def Test_disassemble_closure()
   unlet g:Get
 enddef
 
+def s:ClosureArg(arg: string)
+  var Ref = () => arg .. "x"
+enddef
+
+def Test_disassemble_closure_arg()
+  var res = execute('disass s:ClosureArg')
+  assert_match('<SNR>\d\+_ClosureArg\_s*' ..
+        'var Ref = () => arg .. "x"\_s*' ..
+        '\d FUNCREF <lambda>\d\+',
+        res)
+  var lres = execute('disass ' .. matchstr(res, '<lambda>\d\+'))
+  assert_match('<lambda>\d\+\_s*' ..
+        'return arg .. "x"\_s*' ..
+        '\d LOADOUTER level 1 arg\[-1]\_s*' ..
+        '\d PUSHS "x"\_s*' ..
+        '\d CONCAT size 2\_s*' ..
+        '\d RETURN',
+         lres)
+enddef
 
 def EchoArg(arg: string): string
   return arg
@@ -2664,6 +2683,22 @@ def Test_disassemble_dict_stack()
         res)
 enddef
 
+def s:RetLegacy(): string
+  legacy return "yes"
+enddef
+
+def Test_disassemble_return_legacy()
+  var res = execute('disass s:RetLegacy')
+  assert_match('<SNR>\d*_RetLegacy\_s*' ..
+          'legacy return "yes"\_s*' ..
+          '\d CMDMOD legacy\_s*' ..
+          '\d EVAL legacy "yes"\_s*' ..
+          '\d CHECKTYPE string stack\[-1]\_s*' ..
+          '\d CMDMOD_REV\_s*' ..
+          '\d RETURN',
+        res)
+enddef
+
 def s:EchoMessages()
   echohl ErrorMsg | echom v:exception | echohl NONE
 enddef

src/testdir/test_vim9_script.vim

@@ -2376,6 +2376,14 @@ def Test_for_loop_unpack()
       endfor
   END
   v9.CheckDefExecFailure(lines, 'E1017:', 1)
+
+  lines =<< trim END
+      for [a, b] in g:listlist
+        echo a
+      endfor
+  END
+  g:listlist = [1, 2, 3]
+  v9.CheckDefExecFailure(lines, 'E1140:', 1)
 enddef
 
 def Test_for_loop_with_try_continue()

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4835,
 /**/
     4834,
 /**/

src/vim9execute.c

@@ -5571,7 +5571,7 @@ list_instructions(char *pfx, isn_T *instr, int instr_count, ufunc_T *ufunc)
 		break;
 	    case ISN_LOADOUTER:
 		{
-		    if (iptr->isn_arg.number < 0)
+		    if (iptr->isn_arg.outer.outer_idx < 0)
 			smsg("%s%4d LOADOUTER level %d arg[%d]", pfx, current,
 				iptr->isn_arg.outer.outer_depth,
 				iptr->isn_arg.outer.outer_idx