Fix a typo in crashes logging

[dhei]

Looks like a copy-and-paste error. "Failed to send onBeforeSending event:" should be "Failed to send onSendingFailed event:".

[msftclas]

@dhei,
Thanks for your contribution as a Microsoft full-time employee or intern. You do not need to sign a CLA.
Thanks,
Microsoft Pull Request Bot

[guperrot]

yarn.lock should be ignored from git

[dhei]

@guperrot yarn.lock should be checked into source control according to Yarn docs:

All yarn.lock files should be checked into source control (e.g. git or mercurial). This allows Yarn to install the same exact dependency tree across all machines, whether it be your coworker’s laptop or a CI server.