vscode has issues with Inline Souremap Encoding

[t83714]

Currently, the inline sourcemap generated by @std/esm is not in base64 encoding.
Here is one example:

data:application/json;charset=utf-8,%7B%22version%22:3,%22sources%22:%5B%22/Users/user/Development/node_modules/xyz/index.js%22%5D,%22names%22:%5B%5D,%22mappings%22:%22AAAA%22%7D

It seems vscode & chrome inpsector debugger will always assume a data URI for the inline sourcemap is in base64 encoding (even if the ;base64 extension is not included in the data URI scheme).

This will lead to data decoding error. e.g. vscode will report error similart to this:

SourceMaps.getMapForGeneratedPath: exception while processing path: /Users/user/Development/node_modules/toyrobotsimulator/index.js, sourcemap: data:application/json;charset=utf-8,%7B%22version%22:3,%22sources%22:%5B%22/Users/user/Development/node_modules/xyz/index.js%22%5D,%22names%22:%5B%5D,%22mappings%22:%22AAAA%22%7D
SyntaxError: Unexpected token � in JSON at position 0
    at JSON.parse (<anonymous>)

Could we please change the inline sourcemap encoding to base64?

[jdalton]

@t83714

Sure I can! Worth noting I haven't seen the issue using Chrome 61 or with whatever version of inspector Electron uses.

Are you testing with node --inspect? Or uses the inspector within vscode only?

Can you file a bug on vscode too with the version number you've used and steps to perform a simple repro?

[t83714]

Testing with vscode (Version 1.17.0) with node --inspect-brk=43701 -r @std/esm index.js and got the following error:

Debugging with inspector protocol because Node.js v8.6.0 was detected.
node --inspect-brk=43701 -r @std/esm index.js 
Debugger listening on ws://127.0.0.1:43701/47554922-5c90-482e-9126-9a7c3bf70bdf
Debugger attached.
SourceMaps.getMapForGeneratedPath: exception while processing path: /Users/user/Development/xyz/index.js, sourcemap: data:application/json;charset=utf-8,%7B%22version%22:3,%22sources%22:%5B%22/Users/user/Development/xyz/index.js%22%5D,%22names%22:%5B%5D,%22mappings%22:%22AAAA;AACA;AACA;AACA;AACA;AACA%22%7D
SyntaxError: Unexpected token � in JSON at position 0
    at JSON.parse (<anonymous>)
    at new SourceMap (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/ms-vscode.node-debug2/node_modules/vscode-chrome-debug-core/out/src/sourceMaps/sourceMap.js:20:25)
    at sourceMapContentsP.then.contents (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/ms-vscode.node-debug2/node_modules/vscode-chrome-debug-core/out/src/sourceMaps/sourceMapFactory.js:53:28)

Had another try. It works on lastest Chrome (Version 61.0.3163.100) now.
Could be the outdated version that caused the issue. Sorry for the confusion.

Have filed a bug on vscode for this issue 35978

Thanks!

[jdalton]

Thanks!

I'll defer to the vscode bug.

Update:

Root caused to convert-source-map dep; thlorenz/convert-source-map#59.

[t83714]

Any chance for the future version of @std/esm to use base64 encoded data URI.
The current encoding is correct & valid data URI scheme.
However, many data URI decoder implementation assumes base64 encoding by default incorrectly --- tried a few online decoder and it seems many of them didn't work properly.
Change it to base64 will make it less chance it to break --- even it's the issue of other libs.

[jdalton]

My main concern is node --inspect and Chromium based inspecting (through Electron). Since those cases are covered I rather avoid the overhead of base64 encoding if possible since the source mapping is just a nice-to-have way to avoid seeing the instrumented code behind the scenes.

I'm OK with punting this to vscode or its dependencies.

[t83714]

No problem. Thanks for the note.

[Pokute]

This bug still happens and it is as you've thought, @jdalton. VSCode's node debugger expects that source maps are formatted in base64. I've managed to hack it to work, but it'll take a while until I can do a PR for ms-vscode.node-debug.

[jdalton]

Hi @Pokute!

I'm following along on the VSCode side and have volunteered to do a PR too. If you beat me to it that's great as well. I imagine it's just a few lines. I've outlined the function to modify in the issue thread. See microsoft/vscode#35978 (comment).

Update:

Thanks @Pokute for patching it! It should land in tomorrow's Insiders build.