relative paths in sources are not made relative to output file after being resolved.

[krisselden]

in

a/dist/index.js
a/dist/index.map ../src/index.ts
a/src/index.ts
b/dist/index.js
b/dist/index.map  ../src/index.ts
b/src/index.ts

out

bundle.js
bundle.map  sources: ['../src/index.ts', '../src/index.ts']

expected

bundle.js
bundle.map  sources: ['a/src/index.ts', 'b/src/index.ts']

[krisselden]

basically if the baseDir replace was done on the fullPath here https://github.com/ef4/fast-sourcemap-concat/blob/master/lib/source-map.js#L308 but instead it is the relative one is a possible solution