Launchdarkly errors in Rails console: "#<NoMethodError: undefined method `keys' for nil:NilClass>"

[AndrewRayCode]

Describe the bug
Starting a Rails console on a server with Launchdarkly logs an error.

To reproduce
Start a Rails console on a server with the ldclient-rb gem installed

Expected behavior
No errors

Logs
#<NoMethodError: undefined method `keys' for nil:NilClass>

/usr/local/rvm/gems/ruby-2.5.1@project/gems/ldclient-rb-5.4.1/lib/ldclient-rb/user_filter.rb:37:in `filter_values'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/ldclient-rb-5.4.1/lib/ldclient-rb/user_filter.rb:18:in `transform_user_props'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/ldclient-rb-5.4.1/lib/ldclient-rb/events.rb:392:in `make_output_event'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/ldclient-rb-5.4.1/lib/ldclient-rb/events.rb:338:in `block in make_output_events'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/ldclient-rb-5.4.1/lib/ldclient-rb/events.rb:338:in `map'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/ldclient-rb-5.4.1/lib/ldclient-rb/events.rb:338:in `make_output_events'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/ldclient-rb-5.4.1/lib/ldclient-rb/events.rb:295:in `run'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/ldclient-rb-5.4.1/lib/ldclient-rb/events.rb:226:in `block in trigger_flush'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/ldclient-rb-5.4.1/lib/ldclient-rb/non_blocking_thread_pool.rb:25:in `block in post'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:348:in `run_task'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:337:in `block (3 levels) in create_worker'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:320:in `loop'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:320:in `block (2 levels) in create_worker'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:319:in `catch'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/concurrent-ruby-1.0.5/lib/concurrent/executor/ruby_thread_pool_executor.rb:319:in `block in create_worker'
/usr/local/rvm/gems/ruby-2.5.1@project/gems/logging-2.2.2/lib/logging/diagnostic_context.rb:474:in `block in create_with_logging_context'

SDK version
ldclient-rb (5.4.3)

Language version, developer tools
Ruby, Rails 5.2

OS/platform
Ubuntu

[eli-darkly]

The behavior of the code that the stacktrace is pointing to depends on the user properties that you have passed to the variation method, so just saying "on a server with LaunchDarkly" is not enough information for us to reproduce or diagnose this problem.

Could you provide an example of the user properties you're using (with any sensitive identifiers X'd out)?

[eli-darkly]

My best guess, just based on the location of the error, would be that you are putting custom: nil in your user properties. The SDK currently expects custom to either be completely absent or to contain a hash. We can change it to tolerate a nil value there, but the workaround would be simply to not specify the property unless you're going to give a non-nil value.

[eli-darkly]

Fixed in the 5.7.4 release.