On the Rails console, assigning an object to a variable can lead to this strange error (without stacktrace):

irb > recipient = Recipient.find(123)
Traceback (most recent call last):
TypeError (nil can't be coerced into Integer)
irb > recipient
#<Recipient ...

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The error is only in the output – the assignment is working. It only occurs when using the --nomultiline option, and thus only with IRB 1.2.0+ and before Ruby 3 Show archive.org snapshot . Also, it depends on the value of the assignment – not every Recipient (in this example) will trigger it.

Solution

Its cause is in the reline gem Show archive.org snapshot , and the issue is fixed in reline 0.2.0. So either gem install reline, or in projects with Bundler:

gem 'reline', '>= 0.2.0' # Fixes TypeError in Rails console