Validate syntax when a subscription has an invalid label

[DHaussermann]

If a user mistakenly forgets the " on the label, the label has no affect and it's not obvious why.

Ideally we can prevent this by checking if label: is followed by a value in quotes to prevent user error. If we showed a message such as no valid label provided this would be far more forgiving.

Steps:

• type /github subscribe DHaussermann/hello-world pulls,issues,creates,deletes,label:Apples with Apples instead of "Apples"
• Subscription successful

Observed Label has no affect as no valid label was provided

[DHaussermann]

@hanzei please advise if this is technically possible and would make a good help wanted.

[hanzei]

That improvement makes up for a great HW 👍

[NamrataSitlani]

@DHaussermann @hanzei Hi, I would like to assign this issue to myself, and give it a try.

[hanzei]

Awesome, thanks for taking a look @NamrataSitlani. Let me know if you have any questions.