GDScript: properly set type of local variable initialization

Properly sets the type of the identifier for the local variable
that is stored in the assignment operation. This makes sure that the
compiler is aware of typing for local variables when they are
initialized with the declaration.

modules/gdscript/gdscript_parser.cpp

@@ -8047,6 +8047,7 @@ void GDScriptParser::_check_block_types(BlockNode *p_block) {
 
 				last_var_assign = lv->assign;
 				if (lv->assign) {
+					lv->assign_op->arguments[0]->set_datatype(lv->datatype);
 					DataType assign_type = _reduce_node_type(lv->assign);
 #ifdef DEBUG_ENABLED
 					if (assign_type.has_type && assign_type.kind == DataType::BUILTIN && assign_type.builtin_type == Variant::NIL) {