Reverting serialize-error to version 2.1.0

[jespino]

Summary

Reverting serialize-error to version 2.1.0

serialize-error is though for node, and the version 3.0.0 is using ES6 directly, without transpiling anything (added the Node 6 requirement) and it breaks IE11, so... we must stick to 2.1.0 or remove entirely the dependency (is used in one single place, the logError action.

Ticket Link

MM-15285

[jespino]

Other option would be embed the serialize-error code entirely in our code (is not too much code, only 2 functions) and we can remove the dependency entirely, avoiding future upgrades to screw us.

[jespino]

Now I'm starting to think this is more related to babel upgrade, or something like that. I'm still investigating

[jespino]

Finally I can test it, and is a combination of 4 things:

• 1. the development compilation generate a security error (which is not important, because the production build doesn't execute that code).
• 2. The serialize-error dependency here.
• 3. the exif2css dependency in mattermost-webapp.
• 4. a error accessing plugin.initialize when a plugin has fail to initialize.

So I going to make another PR in mattermost-webapp to fix everything else.