Unable to concatenate file with multiple sourcemaps

[mattdsteele]

I've built a UMD bundle with Webpack 3.0.0, using devtool: '#source-map' as my source map generation option. It ends up producing a build with multiple //# sourceMappingUrl pragmas. For example:

/******/ ([
/* 0 */
/***/ (function(module, exports) {

module.exports = __WEBPACK_EXTERNAL_MODULE_0__;

/***/ }),
/* 1 */
/***/ (function(module, exports, __webpack_require__) {
 /// code
};
//# sourceMappingURL=common.js.map

/***/ }),
/* 2 */
/***/ (function(module, exports, __webpack_require__) {

"use strict";
 /// code
};
//# sourceMappingURL=predicates.js.map

/// etc, to end of file:
//# sourceMappingURL=build.js.map

Only the final build.js.map exists on disk. But this code finds the first sourceMappingUrl and attempts to read it, which results in errors such as:

Warning: Unable to read "C:\code\node_modules\sample\common.js.map" file (Error code: ENOENT). Use --force to continue.

I'm not familiar enough with the source map spec to know how to resolve this, but other tools (gulp, Chrome) seem to read this file fine.

[skylarmb]

EDIT: I was having this same issue, but I solved it.

Warning: Unable to read ".../assets/bower_components/es6-shim/es6-shim.map" file (Error code: ENOENT). Use --force to continue.

My issue was I was copying bower_components to my build directory but I was only copying *.js and not *.map as well, so the js files referenced source maps that did not exist in my build directory.

[AlmogCohen]

@skylarmb its a little late...but how did you manage to solve that? :) I believe I'm facing the same issue

[skylarmb]

@AlmogCohen My comment describes how i solved it. The sourcemaps were not being copied to the build directory. I believe (hard to remember) i solved this by just copying sourcemaps as well as .js files to the build directory during the build process.