Uncaught TypeError: Cannot read property 'buffer' of undefined

[vmvwebworks]

[Enter steps to reproduce:]

1. ...
2. ...

Atom: 1.28.0 x64
Electron: 2.0.3
OS: Ubuntu 18.04
Thrown From: html2slim package 0.5.0

Stack Trace

Uncaught TypeError: Cannot read property 'buffer' of undefined

At /home/marcos/.atom/packages/html2slim/lib/html2slim.coffee:51

TypeError: Cannot read property 'buffer' of undefined
    at Object.convert (/packages/html2slim/lib/html2slim.coffee:51:23)
    at /packages/html2slim/lib/html2slim.coffee:17:85)
    at CommandRegistry.handleCommandEvent (/usr/share/atom/resources/app/src/command-registry.js:384:49)
    at Object.didConfirmSelection (/usr/share/atom/resources/app/node_modules/command-palette/lib/command-palette-view.js:152:35)
    at SelectListView.confirmSelection (/usr/share/atom/resources/app/node_modules/atom-select-list/src/select-list-view.js:401:26)
    at SelectListView.didClickItem (/usr/share/atom/resources/app/node_modules/atom-select-list/src/select-list-view.js:287:16)
    at ListItemView.onclick (/usr/share/atom/resources/app/node_modules/atom-select-list/src/select-list-view.js:222:37)
    at ListItemView.didClick (/usr/share/atom/resources/app/node_modules/atom-select-list/src/select-list-view.js:449:16)

Commands

     -0:36.2.0 html2slim:convert (input.hidden-input)
     -0:11 command-palette:toggle (atom-pane.pane.active)
     -0:06.6.0 html2slim:convert (atom-pane.pane.active)

Non-Core Packages

atom-material-ui 2.1.3 
autumn-highlighter-syntax 1.13.0 
city-lights-syntax 1.1.8 
git-time-machine 2.1.0 
html2slim 0.5.0 
language-slim 1.0.0 
linter-slim 1.0.0 
minimap 4.29.8 
ruby-block 0.3.6 
ruby-slim 0.2.0 
slim-language 2.2.0