This adds a client side error logger that will store errors
in EventLogging. We will use it to get a sense of the number
of errors inside mobile.
To enable make use of the new configuration variable
wgMinervaErrorLogSamplingRate = 1
Notes:
* the optional `meta` field will not be utilised by the generic
error handler.
* URI length is not trimmed for title. We will consider whether we need
to make any adjustments to the schema values during roll out.
** For stack trace, we limit the length by removing errorUrl (which is logged
separately)
Testing:
Add throw new Error('asasasa'); anywhere in your code and make
sure the code executes. It should trigger an Error event provided
that configuration has been updated.
Bug: T202026
Change-Id: I07f01b4c025b2e5e4cbf88ec05e7c536442c62cc
