Version
v24.13.0
Platform
Darwin robhogan-mac 25.1.0 Darwin Kernel Version 25.1.0: Mon Oct 20 19:34:05 PDT 2025; root:xnu-12377.41.6~2/RELEASE_ARM64_T6041 arm64
Subsystem
readline
What steps will reproduce the bug?
// readline-repro.js
const readline = require('readline');
const {Readable} = require('stream');
const input = Readable.from([]);
input.onHistoryFileLoaded = () => 'oops';
readline.createInterface(input);How often does it reproduce? Is there a required condition?
Always
What is the expected behavior? Why is that the expected behavior?
Prior to Node v24.2.0, this did not crash
What do you see instead?
node readline-repro.js
node:internal/readline/interface:571
this.input.pause();
^
TypeError: Cannot read properties of undefined (reading 'pause')
at Interface.pause (node:internal/readline/interface:571:16)
at ReplHistory.initialize (node:internal/repl/history:111:20)
at Interface.setupHistoryManager (node:internal/readline/interface:392:27)
at Interface.InterfaceConstructor (node:internal/readline/interface:218:8)
at new Interface (node:readline:115:3)
at Object.createInterface (node:readline:212:10)
at Object.<anonymous> (/private/tmp/readline-repro.js:6:21)
at Module._compile (node:internal/modules/cjs/loader:1734:14)
at Object..js (node:internal/modules/cjs/loader:1899:10)
at Module.load (node:internal/modules/cjs/loader:1469:32)
Node.js v24.2.0
Additional information
The example is contrived (what are we doing assigning onHistoryFileLoaded anyway?) but we hit this in the wild in a Node.js update when passing jest.mock() as the input. Rightly or wrongly, jest-mock by default uses a proxy object to create properties as mock functions on access.
So a more real-world issue would be:
// readline-test.js
const readline = require('readline');
readline.createInterface(jest.mock());Now crashes.
I root caused this to #58225. Repeating here:
setupHistoryManager is called within InterfaceConstructor, here:
|
this.setupHistoryManager(input); |
Note that's before this.input is assigned, here:
Which is a problem because setupHistoryManager may call initialize()
|
setupHistoryManager(options) { |
|
this.historyManager = new ReplHistory(this, options); |
|
|
|
if (options.onHistoryFileLoaded) { |
|
this.historyManager.initialize(options.onHistoryFileLoaded); |
|
} |
Which tries to call .pause() on the interface's input property (still before it has been assigned)
CC @puskin
Reacted by Rob Hogan
Version
v24.13.0
Platform
Subsystem
readline
What steps will reproduce the bug?
How often does it reproduce? Is there a required condition?
Always
What is the expected behavior? Why is that the expected behavior?
Prior to Node v24.2.0, this did not crash
What do you see instead?
Additional information
The example is contrived (what are we doing assigning
onHistoryFileLoadedanyway?) but we hit this in the wild in a Node.js update when passingjest.mock()as theinput. Rightly or wrongly,jest-mockby default uses a proxy object to create properties as mock functions on access.So a more real-world issue would be:
Now crashes.
I root caused this to #58225. Repeating here:
setupHistoryManageris called withinInterfaceConstructor, here:node/lib/internal/readline/interface.js
Line 218 in 644ba1f
Note that's before
this.inputis assigned, here:node/lib/internal/readline/interface.js
Line 236 in 644ba1f
Which is a problem because
setupHistoryManagermay callinitialize()node/lib/internal/readline/interface.js
Lines 384 to 389 in 644ba1f
Which tries to call
.pause()on the interface'sinputproperty (still before it has been assigned)node/lib/internal/repl/history.js
Line 111 in 644ba1f
CC @puskin