How does variable assignment works in ruby?

Question

Ruby version: ruby 2.6.7p197 (2021-04-05 revision 67941) [x86_64-linux]

Rails gem version: 6.0.1

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Simple question, I have this example on rails console

As expected, if I try to call a non existent variable, I got an error

irb(main):007:0> value
# Traceback (most recent call last):
#         2: from (irb):7
#        1: from (irb):7:in `rescue in irb_binding'
# NameError (undefined local variable or method `value' for main:Object)

But if I try to do the following example

(value = 1) if value.present?

It returns nil for some reason, the first scenario this happenned there was no parenthesis, I thought it was defining the variable and then returning a value of nil, but then I tried with it and just happened again (I tried other variable because ruby counted that as a defined variable)

OBS: I tried the same scenario on raw irb and it raised me an error, this only happens on rails console

EDIT: It only raised an error because I didn't realized that '.present?' is a rails method, but if I change my syntax to

(value = 1) if value

the same behaviour happens

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Why does that happen? Shouldn't a NameError be raised?