give a better error message for option.get

[fwbrasil]

Problem

It's common to have questions on gitter on why option.get doesn't work.

Solution

Give an error message that explains how to fix the issue

Checklist

• Unit test all changes
• Update README.md if applicable
• Add [WIP] to the pull request title if it's work in progress
• Squash commits that aren't meaningful changes
• Run sbt scalariformFormat test:scalariformFormat to make sure that the source files are formatted

@getquill/maintainers