bugfix: empty string is valid for numericopt

[micgro42]

This fixes a bug that the empty string was considered invalid for config entries with type numericopt and a min or max restriction.

Bug Description:

Steps to reproduce

1. create plugin with config-option $conf['foobar'] = ''; in default.php and $meta['foobar'] = array('numericopt', '_min' => 50); in metadata.php
2. go to config-manager and change that value to 100
3. save
4. change that value back to '' (empty string)
5. try to save

actual result: error message that the entered value is invalid

expected result: save is successful, because numericopt value is allow to be an empty string

[mention-bot]

@micgro42, thanks for your PR! By analyzing the history of the files in this pull request, we identified @mperry2, @Chris--S and @Klap-in to be potential reviewers.

[splitbrain]

Hmm. Does that make sense? When I have a numeric config option and specify it should be at least 50, why should I allow an empty value?

[micgro42]

It could be useful to have no value to mean "deactivated" or "auto". The current use case is that the edittable-plugin allows specifying a default-width for the columns. It is sensible to require a minimum width for that default, because a column-width of 5px doesn't make much sense. However I still want to give the user the option (which is also the default value of that config-option) to use handsontable's automatic column-width calculation. That would be (re-)enabled by setting the config value to ''.

Also, if I wouldn't want to allow the empty string, wouldn't it make more sense to just use the numeric type?

[splitbrain]

You're right. I mixed up numeric and numericopt.