Error while creating custom Highchart file

I am getting the below error when trying to run custom-builder
```
➜ node custom-builder.js
fs.js:675
return binding.read(fd, buffer, offset, length, position);
^

Error: EISDIR: illegal operation on a directory, read
at Object.fs.readSync (fs.js:675:18)
at tryReadSync (fs.js:540:20)
at fs.readFileSync (fs.js:583:19)
at getFile (/home/xxxx/Development/mastering-dnd/node_modules/highcharts-assembler/src/utilities.js:61:26)
at getOrderedDependencies (/home/xxxx/Development/mastering-dnd/node_modules/highcharts-assembler/src/dependencies.js:202:19)
at imports.reduce (/home/xxxx/Development/mastering-dnd/node_modules/highcharts-assembler/src/dependencies.js:220:13)
at Array.reduce ()
at getOrderedDependencies (/home/xxxx/Development/mastering-dnd/node_modules/highcharts-assembler/src/dependencies.js:216:18)
at compileFile (/home/xxxx/Development/mastering-dnd/node_modules/highcharts-assembler/src/dependencies.js:503:24)
at getIndividualOptions.forEach (/home/xxxx/Development/mastering-dnd/node_modules/highcharts-assembler/src/build.js:129:26)
```