CLI logging and error handling improvements

[garrettjstevens]

I was running into some problems with the CLI silently failing, so here are some things I found that we need to do to make the CLI error output better:

• Minimize the use of try-catch statements
  • try-catch should only be used when:
  • We need to recover from the error
  • We need to add more context to the error before throwing
  • In most cases we should just let an error happen and let oclif's default error handling take care of it.
• Don't use this.exit
  • Instead of this.exit(1), use this.error('error message here')
  • Instead of this.exit(0), use return or let control flow fall off the end of the method
• Don't use this.logToSterr() or process.stderr.write()
  • If logging an error, log and exit in the same command with this.error()
  • If logging a warning, use this.warn()
• Add this.debug statements sparingly to a few key places in the code so we can use debug logging when we need to know more about what the command is doing.
  • See the debug logs by setting the DEBUG=apollo* environment variable, e.g. DEBUG=apollo* yarn dev assembly get

As an example of a couple points above, something like

this.logToStderr(
  'Error: End coordinate is lower than the start coordinate',
)
this.exit(1)

should become

this.error('End coordinate is lower than start coordinate')

And something like this:

try {
  config = YAML.parse(data)
} catch (error) {
  this.logToSterr('Problem parsing config file')
  this.exit(1)
}

should become

try {
  config = YAML.parse(data)
} catch (error) {
  this.error(error, { suggestions: ['Make sure the config file is a valid YAML document']} )
}