bug(cli): mode flag accepts any value

[snitin315]

Describe the bug

--mode is accepting any value and outputs development build. I can pass --mode=abcd , and it produces the build(development).

Expected behavior
It should accept only production , development or none

[anshumanv]

In case of invalid mode value we can probably use dev mode as default and print a warning that the given mode is invalid so dev will be used by default.

[snitin315]

I will work on this issue.

[anshumanv]

Awesome, thanks!

[ematipico]

You can use type to validate your argument.

https://github.com/75lb/command-line-args/blob/master/doc/option-definition.md#module_option-definition--OptionDefinition+type