Error: CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY

Error:

CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, rsdoc.DocumentActionTriggers: execution of BeforeInsert caused by: System.NullPointerException: Attempt to de-reference a null object Trigger.rsdoc.DocumentActionTriggers: line X, column 1: []

You may see this error while running unit tests to fix, call Opero Documents onInstall method in your test setup:

rsdoc.PostInstallClass classInstanceName = new rsdoc.PostInstallClass();
classInstanceName.onInstall(null);