Unhandled rejection Error: Out of bounds. Invalid column letter:

I'm attempting to read an excel xslx with a drop down column with options as the image shows.

`js-xlsx` doesn't seem a versatile as `exceljs`, except I cannot read this file. It's a file my company uses nationally and would like read and edited through automation.

The error I am getting is

```
Unhandled rejection Error: Out of bounds. Invalid column letter: MONTH
at Object.l2n (C:\Users\Thomas\electron\eqs\node_modules\exceljs\lib\utils\col-cache.js:78:13)
at Object.decodeAddress (C:\Users\Thomas\electron\eqs\node_modules\exceljs\lib\utils\col-cache.js:112:26)
at Object.decodeEx (C:\Users\Thomas\electron\eqs\node_modules\exceljs\lib\utils\col-cache.js:179:21)
at Object.addCell (C:\Users\Thomas\electron\eqs\node_modules\exceljs\lib\utils\cell-matrix.js:36:29)
at C:\Users\Thomas\electron\eqs\node_modules\exceljs\lib\doc\defined-names.js:176:16
at Array.forEach (native)
at Function._.each._.forEach (C:\Users\Thomas\electron\eqs\node_modules\underscore\underscore.js:78:11)
at C:\Users\Thomas\electron\eqs\node_modules\exceljs\lib\doc\defined-names.js:175:9
at Array.forEach (native)
at Function._.each._.forEach (C:\Users\Thomas\electron\eqs\node_modules\underscore\underscore.js:78:11)
at Object.set model [as model] (C:\Users\Thomas\electron\eqs\node_modules\exceljs\lib\doc\defined-names.js:173:7)
at Object.set model [as model] (C:\Users\Thomas\electron\eqs\node_modules\exceljs\lib\doc\workbook.js:146:30)
at C:\Users\Thomas\electron\eqs\node_modules\exceljs\lib\xlsx\xlsx.js:579:31
at tryCatcher (C:\Users\Thomas\electron\eqs\node_modules\bluebird\js\release\util.js:16:23)
at Promise._settlePromiseFromHandler (C:\Users\Thomas\electron\eqs\node_modules\bluebird\js\release\promise.js:502:31)
at Promise._settlePromise (C:\Users\Thomas\electron\eqs\node_modules\bluebird\js\release\promise.js:559:18)
```

Line 78 of col-cache.js is:

```
if (!this._l2n[l]) {
throw new Error('Out of bounds. Invalid column letter: ' + l);
}
```

So the problem is with the columns because simplier xlsx files are read.

Does anyone have a clue how I can fix or bypass this? If I was writing, as @jozsi and @barbalex, that solution would work. Any help? Thanks in advance.