DashParser no longer throws manifestError on invalid MPD, player throws Uncaught TypeError

Created by: davemevans

Since 2.6.3, DashParser no longer throws a manifestError and instead always returns a valid XML document containing only a parsererror node. Instead of failing gracefully and informing the top-level application, the player simply fails with an Uncaught TypeError the first time some assumption about the manifest isn't met (i.e almost immediately)

The following MPD will cause this issue: <MPD></MPD

This is due to https://github.com/Dash-Industry-Forum/dash.js/pull/2237 - that patch is looking for parseerror - it should be looking for parsererror (embarrassing since I +1'ed that PR 😊)