JS error occurs after applying inline style for text in a table created in RichText field.

Steps to reproduce:
1. Create a custom inline style (https://doc.ezplatform.com/en/latest/guide/extending_online_editor/#custom-styles),
2. Create new content (with a RichText field)
3. Add a table in RichText field
4. Write some text in one of the table cells
5. Select the text and apply an inline style
6. Click outside the cell with that text and click again on the text

Result:
JS error occurs:

b22ba31.js:149 Uncaught TypeError: Cannot read property 'getStyle' of null
    at t.value (9ff49d9.js:20)
    at t.getStateClasses (99d1470.js:848)
    at t.value (9ff49d9.js:20)
    at Wf (b22ba31.js:114)
    at wh (b22ba31.js:125)
    at kg (b22ba31.js:143)
    at lg (b22ba31.js:143)
    at fc (b22ba31.js:150)
    at vb (b22ba31.js:149)
    at ub (b22ba31.js:149)

Expected:
The user can edit text with inline style