Properly format errors, avoid erroring after already triggering an error

[alerque]

• chore(deps): Depend on snafu for more robust error handling
• feat(cli): Output runtime errors pretty-printed for readability
• refactor(cli): Bubble-up more error conditions
• fix(outputters): Don't attempt to create output if we error before processing even starts
• fix(core): Avoid internal error when also erroring due to user provided content errors
• chore(tooling): Drop now obsolete lint exception for non-standard globals
• style(tooling): Restyle Lua code with stylua