[BUG] Invalid sourceMappingURL in bundle output

[limulus]

Bug Report Quick Checklist

• I am on the latest version of Snowpack & all plugins.
• I use package manager npm
• I run Snowpack on macOS
• I run Snowpack on Node.js v14.16.1

Describe the bug

When using optimize.bundle, the sourceMappingURL comment at the end of the file contains extraneous slashes that cause browsers not to be able to load the source map.

To Reproduce

1. npm init snowpack-app --template @snowpack/app-template-react
2. Uncomment "bundle": true in snowpack.config.js. (If [BUG] Built-in optimizations doesn't respect sourcemap option #2935 is already fixed you should also add sourcemap: true to optimize)
3. Run npm run build
4. View last line of build/dist/index.js and observe the sourceMappingURL value: //# sourceMappingURL=//dist//index.js.map
5. Optional: Load build/dist/index.html in a browser, bring up the browser’s dev tools, and see it fail to load the source map file because it interprets it as a scheme relative URL with a host of dist.

Expected behavior

The sourceMappingURL value should be a valid URL. Probably just a relative URL like index.js.map.

[Lyanthropos]

Probably the same underlying issue as #3110 and #3111

[drwpow]

Thanks for raising! Yes it might be related to #3110 and #3111, but overall this is a symptom of needing better sourcemap support in general in Snowpack. A lot of people have asked for better sourcemap support and we’re working on it now! In that light, I’m going to close this in favor of our current issue for tracking: #1213

[limulus]

Confirmed that this is fixed in v3.3.3! 👍