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SyntaxError: Unexpected token z in JSON at position 0 #254

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provegard opened this issue Oct 12, 2019 · 3 comments · Fixed by 42technologies/node-source-map-support#1 · May be fixed by #283
Open

SyntaxError: Unexpected token z in JSON at position 0 #254

provegard opened this issue Oct 12, 2019 · 3 comments · Fixed by 42technologies/node-source-map-support#1 · May be fixed by #283

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@provegard
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I have the following situation:

  • I start Karma with `node --require coffeescript/register' since my Karma config is in CoffeeScript
  • Karma loads ts-node to support TypeScript modules
  • I have a custom Karma preprocessor for compiling CoffeeScript, since karma-coffee-preprocessor doesn't support CoffeeScript 2.
  • I configure CoffeeScript to transpile the resulting JS code with Babel
  • I use Babel's preset-env
  • Babel loads a plugin, plugin-proposal-async-generator-functions, which uses @babel/template which creates a stack trace by throwing and catching an Error (inside a function called extendedTrace).
  • When this happens, source-map-support's prepareStackTrace method is called, since source-map-support is used by ts-node.
  • source-map-support encounters coffeescript.js in the call stack (since the Error is thrown inside Babel which is invoked from CoffeeScript).
  • coffeescript.js contains code for emitting source maps, so it contains code that matches the regular expression used by retrieveSourceMapURL.
  • retrieveSourceMapURL extracts the following source map from coffeescript.js: "zw(u�"
  • This string is passed to source-map which tries to parse it as JSON in parseSourceMapInput.
  • At this point, bad things happen. :-)

I created a git repo that demonstrates the problem: https://github.com/provegard/sourcemap-bug

Clone it, run npm install and then npm test. It produces the following output:

undefined:1
zw(u�
^

SyntaxError: Unexpected token z in JSON at position 0
    at JSON.parse (<anonymous>)
    at Object.parseSourceMapInput (C:\kod\projects\sourcemap-bug\node_modules\source-map-support\node_modules\source-map\lib\util.js:433:15)
    at new SourceMapConsumer (C:\kod\projects\sourcemap-bug\node_modules\source-map-support\node_modules\source-map\lib\source-map-consumer.js:17:22)
    at mapSourcePosition (C:\kod\projects\sourcemap-bug\node_modules\source-map-support\source-map-support.js:190:14)
    at wrapCallSite (C:\kod\projects\sourcemap-bug\node_modules\source-map-support\source-map-support.js:358:20)
    at C:\kod\projects\sourcemap-bug\node_modules\source-map-support\source-map-support.js:399:26
    at Array.map (<anonymous>)
    at Function.prepareStackTrace (C:\kod\projects\sourcemap-bug\node_modules\source-map-support\source-map-support.js:398:30)
    at prepareStackTrace (internal/errors.js:30:29)
    at process.emit (C:\kod\projects\sourcemap-bug\node_modules\source-map-support\source-map-support.js:457:52)
    at process._fatalException (internal/process/execution.js:146:25)

If I modify retrieveSourceMapURL to print lastMatch, I get:

[
  '//# sourceMappingURL=data:application/json;base64,${encoded}`;',
  'data:application/json;base64,${encoded}`;',
  undefined,
  index: 8757,

Versions:

  • Node v12.5.0
  • npm 6.9.2
  • source-map-support: 0.5.13
danielbayley added a commit to danielbayley/node-source-map-support that referenced this issue Oct 15, 2020
@danielbayley
Fix retrieveSourceMapURL to prevent false matches in CoffeeScript cod…
357f56c 
…ebase

This bug was hard to track down! It breaks all my tests, and has been a real hinderance to my _[jest-preset-coffeescript](https://github.com/danielbayley/jest-preset-coffeescript/runs/1254200867?check_suite_focus=true)_ package. Fixes evanw#254.
@danielbayley danielbayley linked a pull request Oct 15, 2020 that will close this issue
Open
danielbayley added a commit to danielbayley/source-map that referenced this issue Oct 15, 2020
@danielbayley
Ignore false matches from CoffeeScript codebase
81a1a95 
I'm not sure this is the best fix for this bug, which was hard to track down! But I have also attempted to address it here: evanw/node-source-map-support#283 although looking at the activity on that repo, I don't have much hope of it being merged any time soon… Hence the reason for this PR.

See also: evanw/node-source-map-support#254
@danielbayley danielbayley mentioned this issue Oct 15, 2020
Open
danielbayley added a commit to danielbayley/jest-preset-coffeescript that referenced this issue Oct 15, 2020
@danielbayley
Fix CI
be178c9 
See evanw/node-source-map-support#254 for details.
danielbayley added a commit to danielbayley/jest-preset-coffeescript that referenced this issue Oct 15, 2020
@danielbayley
Fix CI
9cba6d4 
See evanw/node-source-map-support#254 for details.
danielbayley added a commit to danielbayley/jest-preset-coffeescript that referenced this issue Oct 16, 2020
@danielbayley
Fix source-map-support bug
183ec03 
See evanw/node-source-map-support#254.
@bazineta
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I landed here after just a lot of failing to get a coffeescript preset working with Jest. The one-liner provided by @danielbayley works for us.

@MicMonen
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MicMonen commented Aug 9, 2022

I got the same error using coffee, also don't see the code daniel committed anymore.

@ivands
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ivands commented Aug 9, 2022

Same error with the coffeescript preset in jest.
Please fix it.

This was referenced Nov 28, 2022
Merged
Merged
surjikal pushed a commit to 42technologies/source-map that referenced this issue May 1, 2023
@danielbayley
Ignore false matches from CoffeeScript codebase
2d3b249 
I'm not sure this is the best fix for this bug, which was hard to track down! But I have also attempted to address it here: evanw/node-source-map-support#283 although looking at the activity on that repo, I don't have much hope of it being merged any time soon… Hence the reason for this PR.

See also: evanw/node-source-map-support#254
surjikal added a commit to 42technologies/source-map that referenced this issue May 6, 2023
@surjikal
Ignore false matches from CoffeeScript codebase
9639154 
I'm not sure this is the best fix for this bug, which was hard to track down! But I have also attempted to address it here: evanw/node-source-map-support#283 although looking at the activity on that repo, I don't have much hope of it being merged any time soon… Hence the reason for this PR.

See also: evanw/node-source-map-support#254
# Conflicts:
#	lib/util.js
surjikal added a commit to 42technologies/source-map that referenced this issue May 6, 2023
@surjikal
Ignore false matches from CoffeeScript codebase
d4ef930 
I'm not sure this is the best fix for this bug, which was hard to track down! But I have also attempted to address it here: evanw/node-source-map-support#283 although looking at the activity on that repo, I don't have much hope of it being merged any time soon… Hence the reason for this PR.

See also: evanw/node-source-map-support#254
# Conflicts:
#	lib/util.js
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@bazineta @provegard @ivands @MicMonen