Ensure vdp failure latching

src/vdp_pesi.c

@@ -1059,7 +1059,9 @@ vdp_pesi_bytes(struct req *req, enum vdp_action act, void **priv,
 			if (pecx->state == 3 && len > 0)
 				retval = VDP_bytes(req, act, pp, len);
 			pecx->l -= len;
-			return (tree->retval);
+			if (retval)
+				break;
+			return (0);
 		case 99:
 			/*
 			 * VEP does not account for the PAD+CRC+LEN
@@ -1100,7 +1102,7 @@ vdp_pesi_bytes(struct req *req, enum vdp_action act, void **priv,
 			break;
 		}
 		if (retval)
-			return (retval);
+			tree->retval = retval;
 		if (tree->retval)
 			return (tree->retval);
 	}