Prevent source map console warnings caused by MetaMask bundles

[MicahZoltu]

Describe the bug
When I open the browser console on any page in my browser I get warnings about being unable to find source maps for MetaMask's sourcemaps/contentscript.js and sourcemaps/inpage.js.map. It would be great if having MetaMask installed didn't result in an error in my console on every page I load.

To Reproduce
Steps to reproduce the behavior:

1. Install MetaMask into Firefox.
2. Open console.
3. Notice the "source map error" warnings.

Expected behavior
No errors in my console when loading a page with MetaMask injected into it.

Screenshots
N/A

Browser details (please complete the following information):

• OS: Windows 10
• Browser: Firefox
• MetaMask Version: 7.0.1

Additional context
Since this is an extension, the size increase from source maps should not be significant enough to cause any problems, as they aren't loaded on every page load and users are accustomed to extensions having non-zero download times. You may need to make the sourcemaps web accessible, though testing is necessary to figure out whether that is required for Firefox to be able to fetch a source map.

[ForbiddenEra]

Oh, so this isn't because of libraries loaded on my webpage.. it's because of an extension.. annoying.. totally thought it was something else (had a few sourcemap errors, a couple were something else) but once I disabled metamask, no errors. Was getting annoying.

Will have to keep metamask disabled now and only enable it when needed.

+1

[abitrolly]

The same problems with latest MetaMask 7.3.1 on Firefox 70.

[abitrolly]

Source map processing starts in

metamask-extension/gulpfile.js

Line 595 in eed4a9e

function bundleTask (opts) {

[abitrolly]

Source maps are processed in bundleTask function. This is as far as I could get.

metamask-extension/gulpfile.js

Line 595 in eed4a9e

function bundleTask (opts) {

Now need to evaluate how big they are and how to best handle them. Are they fetched only when errors occur, or need to be present always?

[abitrolly]

The path to sourcemaps is specified as relative during the build process.

metamask-extension/gulpfile.js

Line 406 in eed4a9e

sourceMapDir: '../sourcemaps',

And the same path is shown when inspecting MetaMask extension from about:debugging#/runtime/this-firefox.

Judging be extension path all scripts are in root and there is no parent directory. Need see if the sourcemaps are inside the downloaded extension and where are they unpacked.

[abitrolly]

GitHub silently eats my comments. Attempt no.3 to paste the link to code section where source maps are generated.

metamask-extension/gulpfile.js

Line 595 in eed4a9e

function bundleTask (opts) {

[abitrolly]

GitHub silently eats my comments. Attempt no.3 to paste the link to code section where source maps are generated.

metamask-extension/gulpfile.js

Line 595 in eed4a9e

function bundleTask (opts) {

[MicahZoltu]

Extension size-on-disk is much less meaningful than web app size-on-disk. That being said, source maps are fetched lazily, when someone opens their browser debugger. The extension however should probably ship with them so that when the browser does ask for them, they are present.

[abitrolly]

I checked my profile dir, found MetaMask extension bundled in .xpi file, and there are no .map files or sourcemaps dir inside. They need to be either bundled or provided through CDN. (IPFS?)

[abitrolly]

Extension size-on-disk is much less meaningful than web app size-on-disk

Which web app do you refer to? MetaMask in archived form of .xpi takes 10Mb. I don't have toolchain ready to compile sourcemaps and see how much do they take.

[abitrolly]

Instead of shipping MetaMask with sourcemaps, why minimize scripts in the first place? They are already compressed.

[MicahZoltu]

Original source files are TypeScript I think, so source maps are likely necessary even without minification. That being said, I agree that minification and bundling here hurts rather than helps, but that is just my personal opinion. The missing source maps however cause problems for end users and developers.

[abitrolly]

GitHub tells it is JavaScript, Likely that turning off minification for extension code could remove the pain point.