InteliJ IDEA plugin: Empty value for config-file causes issues on plugin load

[ant-druha]

Reported here https://stackoverflow.com/q/69203962/2000323

I've checked and the plugin has empty value for config-file attribute in the plugin descriptor:

  <depends optional="true" config-file="">org.intellij.scala</depends>

Now it may lead to problem when loading the plugin, see also this comment: https://youtrack.jetbrains.com/issue/IDEA-270963#focus=Comments-27-5056928.0-0

[t-rufang]

Fixed in #5857