Detect expression-like inputs, and warn about missing !expr

[jaredoconnell]

Please describe what you would like to see in this project

Detect expression-like inputs, and warn about missing !expr

Please describe your use case

There are times when a user may forget to specify !expr before an expression. When the user expects their input to be interpreted as an expression, and they forget it, the user may not immediately realize that the expression is being interpreted as a string. It would speed up development to warn the user of this mistake.

Additional context

The alternative would be to make it evaluate everything as a string, but there are times when this would cause more problems. Specifically if they actually need a string to start with $.