pgsql: Verify objects are still live at these points.

lib/modules/Sql.pmod/pgsql.pike

@@ -493,9 +493,11 @@ private void waitauthready() {
 }
 
 protected void destroy() {
+  if (proxy) {
     proxy.unnamedstatement = 0;		// Forget about pending statements
     destruct(proxy);
   }
+}
 
 //! For PostgreSQL this function performs the same function as @[resync()].
 //!

lib/modules/Sql.pmod/pgsql_util.pmod

@@ -712,6 +712,7 @@ outer:
     };
     PD("Connect error %s\n", describe_backtrace(err));
     catch(destruct(pgsqlsess->waitforauthready));
+    if (this)
       destruct(this);
   }