Which error do I report?

Section 4.3.1. reads in part:


   1.

   If the process to apply description fails for any reason, then user
   agent must queue a task runs the following steps:
   1.

      If connection's [[isClosed
      <http://w3c.github.io/webrtc-pc/#dfn-isclosed>]] slot is true, then
      abort these steps.
      2.

      If elements of the SDP were modified in an invalid way as specified
      in [JSEP <http://w3c.github.io/webrtc-pc/#bib-JSEP>] (section 6.
      <https://tools.ietf.org/html/draft-ietf-rtcweb-jsep-14#section-6>),
      then reject p with an InvalidModificationError and abort these steps.
      3.

      If the description's type
      <http://w3c.github.io/webrtc-pc/#dom-rtcsessiondescription-type> is
      wrong for the current signaling state
      <http://w3c.github.io/webrtc-pc/#dfn-signaling-state> of connection,
      then reject p with aInvalidStateError and abort these steps.
      4.

      If the content of description is invalid, then reject p with an
      InvalidAccessError and abort these steps.
      5.

      For all other errors, for example if description cannot be applied at
      the media layer, reject p withOperationError.

Consider what happens if I invalidly modify an SDP *and* the PC is in the
wrong state. This algorithm clearly tells you that you should be returning
InvalidModificationError, which doesn't seem sensible.

In general, I don't think the spec should be requiring a specific order of
error checking.

-Ekr