cmd/dev-cmd: improve handling of invalid input

[EricFromCanada]

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Raises errors in more cases of missing or invalid input for various commands. Includes improvements for wording and help text.

[MikeMcQuaid]

Great work so far 👏

[MikeMcQuaid]

I wonder if adding a new exception for this specific case would be a good idea (or even an argument to #parse`) ?

[EricFromCanada]

I took a shot at implementing this in cli/parser; have a look.

[MikeMcQuaid]

Similarly: a new exception or an argument to #parse` might be a better fit?

[EricFromCanada]

⬆️

[MikeMcQuaid]

Amazing work, love where this is going.

[MikeMcQuaid]

Could/should this be a FormulaUnspecifiedError?

[EricFromCanada]

I made these a UsageError with a custom message stating that a formula argument is required only for these specific flags, rather than the command in general, as is implied in the wording of FormulaUnspecifiedError.

[MikeMcQuaid]

Gotcha 👍

[MikeMcQuaid]

Fantastic work as usual @EricFromCanada!