SyntaxError: Invalid or unexpected token

The error

$ node app.js
C:\work\app\app.js:1
const lines = items.join('
                         ^

SyntaxError: Invalid or unexpected token

The line and the caret show where Node gave up.

Why it happens

A string that runs onto the next line. A string in ' or " quotes ends with its line, so a real line break inside it is an error. (Strings in backticks may span lines.) Coding agents cause this when they patch a JavaScript file from a Python script: in an ordinary Python string, \n is a line break, so writing join('\n') into the file puts a real line break between the quotes.

src.replace("join(', ')", "join('\n')")    # writes join(' and a line break

Curly quotes. ‘DMN’ or “DMN”, pasted from a document or a chat, aren't quotes to JavaScript, and give the same error.

The fix

In the Python script, a raw string writes the two characters \n, as JavaScript expects:

src.replace("join(', ')", r"join('\n')")

Or edit the file with an edit tool, which writes exactly the text you give it. Retype curly quotes as ' or ". Then check the file parses, without running it:

node --check app.js

The same escape trap in Python's own strings is behind the unicodeescape error.