Text area for params in send transaction widget is having problem with editing json object

[ishantiw]

Expected behavior

Text area for params in send transaction widget should accept JSON and also allow users to edit properly.

Actual behavior

Currently, when a user pastes a json param object in the text area it doesn't allow users to edit it properly and it shows cursor is at the wrong place while editing

Steps to reproduce

try and paste below in Text area for params in send transaction widget

{
    "numberOfSignatures": 2,
    "optionalKeys": ["508a965871253595b362f8dc27bff6e67b39bdd466531be9c6f8c401253979c",
                    "a9a3c363a71a3089566352127cf0e6f79d3834e1d67b4132b98d35afd3b85375"],
     "mandatoryKeys": ["7720c58afffb0ab6503afe19a1caaacd6c6677df5b97d9c33a117f69860ab686"]
  }

and try to edit or navigate through the text, it will show cursor in different places and it makes it very difficult to edit.
For example in the picture below, I tried to add some text at the end and the cursor position is somewhere in the middle

Which version(s) does this affect? (Environment, OS, etc...)

5.1.0