YAML that starts with comment instead of `--` throws error.

[bnferguson]

When you have a current.yaml that starts with a comment instead of -- you get:

Failure parsing YAML file replicated/current.yaml:
TypeError: Cannot read property 'components' of null

So this is a problem:

# -*- tab-width: 2 -*-
---
replicated_api_version: 2.9.2

but when I change it to:

---
replicated_api_version: 2.9.2

All is well.

If you do this in the releases/ dir in a release YAML you see a stack trace as such:

[getAppUpgrades:1bd2101f] !! 500 TypeError: Cannot read property 'components' of null
    at fillOutDoc (/usr/local/lib/node_modules/replicated-studio/src/replicated/release.ts:68:11)
    at _.map (/usr/local/lib/node_modules/replicated-studio/src/replicated/release.ts:118:34)
    at arrayMap (/usr/local/lib/node_modules/replicated-studio/node_modules/lodash/lodash.js:639:23)
    at Function.map (/usr/local/lib/node_modules/replicated-studio/node_modules/lodash/lodash.js:9554:14)
    at fillOutYamlString (/usr/local/lib/node_modules/replicated-studio/src/replicated/release.ts:110:12)
    at Object.fillOutYaml (/usr/local/lib/node_modules/replicated-studio/src/replicated/release.ts:96:10)
    at _.forEach (/usr/local/lib/node_modules/replicated-studio/src/handlers/getAppUpgrades.ts:34:35)
    at arrayEach (/usr/local/lib/node_modules/replicated-studio/node_modules/lodash/lodash.js:516:11)
    at Function.forEach (/usr/local/lib/node_modules/replicated-studio/node_modules/lodash/lodash.js:9342:14)
    at /usr/local/lib/node_modules/replicated-studio/src/handlers/getAppUpgrades.ts:31:5