patch 8.2.2261: Vim9: boolean option gets string type

Problem:    Vim9: boolean option gets string type.
Solution:   Check for VAR_BOOL. (closes #7588)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index b483a60..d44fe48 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -3172,8 +3172,9 @@
     if (ret == OK)
     {
 	// include the '&' in the name, eval_option() expects it.
-	char_u *name = vim_strnsave(start, *arg - start);
-	type_T	*type = rettv.v_type == VAR_NUMBER ? &t_number : &t_string;
+	char_u	*name = vim_strnsave(start, *arg - start);
+	type_T	*type = rettv.v_type == VAR_BOOL ? &t_bool
+			  : rettv.v_type == VAR_NUMBER ? &t_number : &t_string;
 
 	ret = generate_LOAD(cctx, ISN_LOADOPT, 0, name, type);
 	vim_free(name);