patch 8.2.0972: Vim9 script variable declarations need a type

Problem:    Vim9 script variable declarations need a type.
Solution:   Make "let var: type" declare a script-local variable.
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 17c16d8..9029a48 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -2255,7 +2255,8 @@
 }
 
 /*
- * Find "name" in imported items of the current script/
+ * Find "name" in imported items of the current script or in "cctx" if not
+ * NULL.
  */
     imported_T *
 find_imported(char_u *name, size_t len, cctx_T *cctx)
@@ -5012,12 +5013,12 @@
     }
     else if (cmdidx == CMD_const)
     {
-	emsg(_("E1021: const requires a value"));
+	emsg(_(e_const_req_value));
 	goto theend;
     }
     else if (!has_type || dest == dest_option)
     {
-	emsg(_("E1022: type or initialization required"));
+	emsg(_(e_type_req));
 	goto theend;
     }
     else