When writing debug HTML, don't crash on procs with empty bodies.

Reviewed By: ddino

Differential Revision: D15512985

fbshipit-source-id: 2371486b8

infer/src/backend/printer.ml

@@ -171,9 +171,10 @@ module ProcsHtml : sig
 end = struct
   let write pdesc =
     let pname = Procdesc.get_proc_name pdesc in
-    let source = (Procdesc.get_loc pdesc).file in
+    let loc = Procdesc.get_loc pdesc in
+    let source = loc.file in
     let nodes = List.sort ~compare:Procdesc.Node.compare (Procdesc.get_nodes pdesc) in
-    let linenum = (Procdesc.Node.get_loc (List.hd_exn nodes)).Location.line in
+    let linenum = loc.Location.line in
     let fd, fmt = Io_infer.Html.create source [Typ.Procname.to_filename pname] in
     F.fprintf fmt "<center><h1>Procedure %a</h1></center>@\n"
       (Io_infer.Html.pp_line_link source