patch 8.2.2895: Vim9: random characters appear in some error messages

Problem:    Vim9: random characters appear in some error messages.
Solution:   Pass the correct pointer. (closes #8277)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index cb91c3c..995c1d7 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -5187,7 +5187,7 @@
 	if (!IS_WHITE_OR_NUL(**arg) || !IS_WHITE_OR_NUL(p[1 + op_falsy]))
 	{
 	    semsg(_(e_white_space_required_before_and_after_str_at_str),
-						  op_falsy ? "??" : "?", *arg);
+						     op_falsy ? "??" : "?", p);
 	    return FAIL;
 	}