Uncaught ReferenceError: __CUSTOM_HTML_ELEMENTS_CLASSES__ is not defined

[Enter steps to reproduce:]

1. Right click on .csv file in finder and select open with atom
2. Didn't change any options and clicked Open Table Editor
3. Error appeared

**Atom**: 1.53.0 x64
**Electron**: 6.1.12
**OS**: macOS 11.1
**Thrown From**: [tablr](https://github.com/abe33/atom-tablr) package 1.8.3

### Stack Trace

Uncaught ReferenceError: __CUSTOM_HTML_ELEMENTS_CLASSES__ is not defined

```
At /Users/peterdye/.atom/packages/tablr/node_modules/atom-utils/lib/register-or-update-element.js:55

ReferenceError: __CUSTOM_HTML_ELEMENTS_CLASSES__ is not defined
at module.exports (/packages/tablr/node_modules/atom-utils/lib/register-or-update-element.js:55:5)
at element (/packages/tablr/lib/decorators/element.js:6:10)
at Function.initClass (/packages/tablr/lib/csv-progress-element.js:11:12)
at /packages/tablr/lib/csv-progress-element.js:59:37)
at /packages/tablr/lib/csv-progress-element.js:61:3)
at Module.get_Module._compile (/Applications/Atom.app/Contents/Resources/app/static/:11:147498)
at Object.value [as .js] (/Applications/Atom.app/Contents/Resources/app/static/:11:151046)
at Module.load (internal/modules/cjs/loader.js:645:32)
at Function.Module._load (internal/modules/cjs/loader.js:560:12)
at Module.require (/app.asar/static/index.js:72:46)
at require (/Applications/Atom.app/Contents/Resources/app/static/:11:146814)
at HTMLElement.displayProgress (/packages/tablr/lib/csv-editor-element.js:198:28)
at HTMLElement.ensureProgress (/packages/tablr/lib/csv-editor-element.js:193:39)
at /packages/tablr/lib/csv-editor-element.js:61:12
at Function.simpleDispatch (/Applications/Atom.app/Contents/Resources/app/static/:11:1190051)
at Emitter.emit (/Applications/Atom.app/Contents/Resources/app/static/:11:1191492)
at CSVEditor.openTableEditor (/packages/tablr/lib/csv-editor.js:270:18)
at /packages/tablr/lib/csv-editor-element.js:154:20)
at HTMLButtonElement.listener (/packages/tablr/node_modules/atom-utils/lib/mixins/events-delegation.js:108:41)
```

### Commands

```
```

### Non-Core Packages

```
arduino-upload 1.8.0
atom-clock 0.1.18
atom-ide-debugger-python 0.7.3
atom-ide-outline 1.16.0
atom-ide-ui 0.13.0
file-icons 2.1.46
ide-python 1.7.2
ide-rust 0.22.0-beta.3
kite 0.197.0
language-arduino 0.4.3
language-cython 0.3.0
language-matlab 0.2.1
minimap 4.38.2
pdf-view 0.72.0
platformio-ide-terminal 2.10.1
python-debugger 0.2.0
python-tools 0.6.9
tablr 1.8.3
```

The error originates in /packages/tablr/node_modules/atom-utils/lib/register-or-update-element.js at line 55, referencing an undefined __CUSTOM_HTML_ELEMENTS_CLASSES__. Start by examining that file and its usage in the tablr package, particularly in lib/decorators/element.js and lib/csv-progress-element.js. Check if the variable is declared or imported. The fix likely involves ensuring the variable is defined before use. Test by reproducing the error by opening a CSV file with Atom and clicking 'Open Table Editor'.

Escrito por el modelo de indexación a partir del texto del issue.