Fix --upload-sources stream/buffer logic

[bengourley]

During the refactor for #40, the wrong variable name was referenced in getSendableSource() which meant that the --upload-sources logic ceased to work, introducing #42.

While tracking this down, I also noticed that --upload-sources was not compatible with relative paths in the source map.

Also while tracking this down I noticed that the error information included in the API response was not surfaced to the user, so I updated the output there.

To test these fixes, using a similar setup at the OP in #42:

npm i -g react-native-cli
react-native init BugsnagSourceMapUploadTest
cd BugsnagSourceMapUploadTest
react-native bundle \
  --platform ios \
  --dev false \
  --entry-file index.js \
  --bundle-output ios-release.bundle \
  --sourcemap-output ios-release.bundle.map

Make sure you have bugsnag-sourcemaps cloned locally (checkout master) and reference it like so:

../../path-to/bugsnag-sourcemaps/cli.js \
  --api-key=YOUR_API_KEY \
  --app-version 1.11.111 \
  --minified-file ios-release.bundle \
  --source-map ios-release.bundle.map \
  --upload-sources

You should see the following error:

[info] Uploading (ios-release.bundle.map)
[error] Error uploading source maps: Unknown read stream path of type "string"

Now check out this branch (bengourley/upload-sources-fix) and repeat – you should see a successful upload (if you used a valid api key) or an API error (invalid API key, uploading source maps for an existing version etc.), showing that the library sent a reasonable request.

[info] Uploading (ios-release.bundle.map)

or

[error] Error uploading source maps: Error: HTTP status 401 received from upload API
    at res.pipe.body (/Users/bengourley/Development/bugsnag-sourcemaps/lib/request.js:40:21)
    at ConcatStream.<anonymous> (/Users/bengourley/Development/bugsnag-sourcemaps/node_modules/concat-stream/index.js:37:43)
    at ConcatStream.emit (events.js:187:15)
    at finishMaybe (/Users/bengourley/Development/bugsnag-sourcemaps/node_modules/readable-stream/lib/_stream_writable.js:620:14)
    at afterWrite (/Users/bengourley/Development/bugsnag-sourcemaps/node_modules/readable-stream/lib/_stream_writable.js:466:3)
    at process._tickCallback (internal/process/next_tick.js:63:19)

You can also use the example TypeScript project to test out the fix for --upload-sources in conjunction with --directory mode:

1. Set "inlineSources": false (or comment out that line) in tsconfig.json
2. npm run build – this will now build without including source content in the map
3. npm run upload-source-maps – this won't include sources
4. npm start – sends an error
5. Check that the error appears in the dashboard, but has no surrounding code
6. npm run upload-source-maps -- --overwrite --upload-sources re-upload source maps but tell it to include the sources
7. npm start – sends another error
8. Verify that the new error has surrounding code (if you are on this branch it should, but on master it won't)

[tomlongridge]

LGTM

[ryanliszewski]

Thanks for getting on this so quickly! @bengourley