[master] d1cea9bb4 add assertions requested by @Dridi

[Nils Goroll]

commit d1cea9bb4b3429b6953ee2d68721c8bb33b8f4d5
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Wed Nov 13 09:33:03 2019 +0100

    add assertions requested by @Dridi

diff --git a/bin/varnishd/cache/cache_vpi.c b/bin/varnishd/cache/cache_vpi.c
index 2a0095f79..1ffc62a3e 100644
--- a/bin/varnishd/cache/cache_vpi.c
+++ b/bin/varnishd/cache/cache_vpi.c
@@ -90,6 +90,8 @@ VPI_vcl_select(VRT_CTX, VCL_VCL vcl)
 	struct req *req = ctx->req;
 
 	CHECK_OBJ_NOTNULL(vcl, VCL_MAGIC);
+	CHECK_OBJ_NOTNULL(req, REQ_MAGIC);
+	CHECK_OBJ_NOTNULL(req->top, REQTOP_MAGIC);
 
 	if (IS_TOPREQ(req) && req->top->vcl0 != NULL)
 		return;		// Illegal, req-FSM will fail this later.