Log an error if we fail to get storage

Conflicts:
	bin/varnishd/cache/cache_fetch.c

bin/varnishd/cache/cache_fetch.c

@@ -858,6 +858,7 @@ vbf_stp_error(struct worker *wrk, struct busyobj *bo)
 	bo->vfc->esi_req = bo->bereq;
 
 	if (vbf_beresp2obj(bo)) {
+		(void)VFP_Error(bo->vfc, "Could not get storage");
 		VSB_delete(synth_body);
 		return (F_STP_FAIL);
 	}