Check if .map.originalPositionFor is a function before executing

[marionebl]

Hardens the structural typecheck performed in mapSourcePosition before executing originalPositionFor methods on sourceMap.map objects.

This addresses a bug I encountered with electron-updater while working on https://github.com/meetalva/alva/, where Promise values somehow end up in sourceMap.map, causing the app to crash with stack traces like this.

-/app.asar/node_modules/source-map-support/source-map-support.js:214
    var originalPosition = sourceMap.map.originalPositionFor(position);
                                         ^

TypeError: sourceMap.map.originalPositionFor is not a function
    at mapSourcePosition (-/app.asar/node_modules/source-map-support/source-map-support.js:214:42)
    at wrapCallSite (-/app.asar/node_modules/source-map-support/source-map-support.js:358:20)
    at -/app.asar/node_modules/source-map-support/source-map-support.js:395:26
    at Array.map (<anonymous>)
    at Function.prepareStackTrace (-/app.asar/node_modules/source-map-support/source-map-support.js:394:24)
    at process.emit (-/app.asar/node_modules/source-map-support/source-map-support.js:453:52)
    at process._fatalException (internal/bootstrap/node.js:488:27)

Unfortunately I don't know how this happens exactly. Debugging this proves rather hard due to the exception only being raised when starting the built electron-builder application.

[marionebl]

Failing Travis jobs seem to be unrelated.

[LinusU]

Sorry for not getting back to you earlier, the Travis failure seems indeed unrelated, will try and fix it...

[LinusU]

Fixed, thanks for the PR!

[marionebl]

Thank you!

[LinusU]

Published as v0.5.10 🚀