Project Structure does not open in a Grails project; "Already disposed: URL=''" in the log

Clicking on File - Project Structure does nothing but throw an exception into the log.

See the attached log.

Not sure how to reproduce - I was adding and removing module dependencies before this happened.

It's a Grails 2.5.1 project.

IntelliJ 2016.1.1, build #IU-145.597.3

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*Imported from [IDEA-155002](https://youtrack.jetbrains.com/issue/IDEA-155002) · Type: Bug · Votes: 0*
*Comments, attachments, dates and reporter are not part of the export — follow the link above for the full history.*

Start by reproducing File - Project Structure in a Grails 2.5.1 project, especially after adding and removing module dependencies. Inspect the attached log for the "Already disposed: URL=''" exception and trace the project-structure entry point. Done means the dialog opens without that exception; the issue does not name a source file or test.

Written by the indexing model from the issue text.