Add sanitization, validation, and basic tests for the error_count input parameter.

Some possible rules:

• ensure it is a finite number
• ensure it is greater than 0
• [optional] ensure it is less than the finalized timeout input parameter value (which may be adjusted to MAX_TIMEOUT, depending on the user's input) divided by the finalized reporting_interval
  • That is optional as it's unlikely that every single status check will report a temporary recoverable error 🤷🏻
  • Also, allowing the users to specify a number greater than that gives them the opportunity to allow as many errors as possible before timing out, which is OK if that's what they really want 🤷🏻

Similar to the a part of the changes made for timeout as shown in PR:

• Timeout fix #170

See also:

• Add sanitization, validation, and basic tests for the reporting_interval input parameter #171