patch 8.2.4662: no error for using out of range list index

Problem:    No error for using out of range list index.
Solution:   Check list index at script level like in compiled function.
            (closes #10051)

src/testdir/test_vim9_assign.vim

@@ -288,6 +288,12 @@ def Test_assign_concat()
     s ..= {a: 2}
   END
   v9.CheckDefAndScriptFailure(lines, ['E1105: Cannot convert dict to string', 'E734: Wrong variable type for .='], 2)
+
+  lines =<< trim END
+      var ls: list<string> = []
+      ls[-1] ..= 'foo'
+  END
+  v9.CheckDefExecAndScriptFailure(lines, 'E684: list index out of range: -1', 2)
 enddef
 
 def Test_assign_register()