patch 8.2.4601: Vim9: not enough test coverage for executing :def function

Problem:    Vim9: not enough test coverage for executing :def function.
Solution:   Add a few more tests.

src/testdir/test_vim9_cmd.vim

@@ -1660,6 +1660,8 @@ def Test_substitute_expr()
   v9.CheckDefFailure(['s/from/\="x")/'], 'E488:')
   v9.CheckDefFailure(['s/from/\="x"/9'], 'E488:')
 
+  v9.CheckDefExecFailure(['s/this/\="that"/'], 'E486:')
+
   # When calling a function the right instruction list needs to be restored.
   g:cond = true
   var lines =<< trim END

src/testdir/test_vim9_func.vim

@@ -4085,6 +4085,19 @@ if has('lua')
     EOF
     assert_equal('val', g:d.key)
   enddef
+
+  def Test_lua_heredoc_fails()
+    var lines = [
+      'vim9script',
+      'def ExeLua()',
+        'lua << trim EOLUA',
+            "x = vim.eval('g:nodict')",
+        'EOLUA',
+      'enddef',
+      'ExeLua()',
+      ]
+    v9.CheckScriptFailure(lines, 'E121: Undefined variable: g:nodict')
+  enddef
 endif
 
 

src/testdir/test_vim9_script.vim

@@ -2003,6 +2003,12 @@ def Test_for_loop()
       endfor
       assert_equal(6, total)
 
+      total = 0
+      for b in 0z010203
+        total += b
+      endfor
+      assert_equal(6, total)
+
       var chars = ''
       for s: string in 'foobar'
         chars ..= s

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4601,
 /**/
     4600,
 /**/