DisplayTable should be documented or a default value ("table" or "div" ?) should be offered.

Then, it requires also to set RLModules and RLStyleModules.

This has probably been introduced by Bryan Davis 2015-04-30 commits:

• rECPAc6913cee6693

• rECPAff7794bf264e

In T105485#1444879, @Dereckson wrote:

This has probably been introduced by Bryan Davis 2015-04-30 commits:

• rECPAc6913cee6693

• rECPAff7794bf264e

Both of those changes introduce default values in $wgContactConfig['default']:

• 'DisplayFormat' => 'table',
• 'RLModules' => array(), 'RLStyleModules' => array(),

SpecialContact::getTypeConfig() should be merging these defaults with the formType specific configuration. Have you possibly added local config via LocalSettings.php or similar that is clobbering the extension provided $wgContactConfig['default'] settings?

Updated https://www.mediawiki.org/w/index.php?title=Extension:ContactPage&diff=1746133&oldid=1656576 with these three new config settings.

Change 224109 had a related patch set uploaded (by BryanDavis):
Add README documentation for DisplayFormat, RLModules and RLStyleModules

https://gerrit.wikimedia.org/r/224109

Thanks for pointing out the need for documentation updates. I had made the classic developer blunder of updating the code and adding comments without making the changes more visible to consumers.

Change 224109 merged by jenkins-bot:
Add README documentation for DisplayFormat, RLModules and RLStyleModules

https://gerrit.wikimedia.org/r/224109

Thanks for the documentation fix, yes it now works as expected.

To simplify this configuration block, what if we edit the code to add empty arrays if omitted?

Or if we do <default values array> + <array in settings>, so we keep sane default values, overwritten by the local config values?

In T105485#1446035, @Dereckson wrote:

Thanks for the documentation fix, yes it now works as expected.

To simplify this configuration block, what if we edit the code to add empty arrays if omitted?

Or if we do <default values array> + <array in settings>, so we keep sane default values, overwritten by the local config values?

I had not noticed before that the recommended way to configure the extension is to override all of the default settings provided by the extension. I think you're right that mixing in some sanity defaults at runtime could be useful.

I got this with the following environment:

• MediaWiki 1.27.4 (f581561) 16:58, 3. Mär. 2018
• PHP 5.6.33-0+deb8u1 (apache2handler)
• MySQL 5.5.59-0+deb8u1
• ContactPage 2.2 (c139343) 00:45, 18. Mai 2016

However I found this to be one of the best failures ever seen for MediaWiki or an extension to it since it directly tell what you have to do to get rid of the issue.

I must note that I only got this because I left the configuration blanc for DisplayFormat