patch 8.2.1813: Vim9: can assign wrong type to script dict

Problem:    Vim9: can assign wrong type to script dict. (Christian J.  Robinson)
Solution:   Check the type if known.
diff --git a/src/proto/vim9script.pro b/src/proto/vim9script.pro
index f8b12ee..a20b715 100644
--- a/src/proto/vim9script.pro
+++ b/src/proto/vim9script.pro
@@ -8,5 +8,6 @@
 int find_exported(int sid, char_u *name, ufunc_T **ufunc, type_T **type);
 char_u *handle_import(char_u *arg_start, garray_T *gap, int import_sid, evalarg_T *evalarg, void *cctx);
 char_u *vim9_declare_scriptvar(exarg_T *eap, char_u *arg);
+svar_T *find_typval_in_script(typval_T *dest);
 int check_script_var_type(typval_T *dest, typval_T *value, char_u *name);
 /* vim: set ft=c : */