Godot: Engine crashes when replacing text in the script editor

[VedatGunel]

Godot version:
v3.2.1 stable
OS/device including version:
Windows 10 64 bit, Version 1909
Issue description:
Engine seems to freeze and not respond in some cases when I try to replace text in the script editor using the replace menu.
Some observations:

• It only seems to happen when "Selection Only" is selected.
• It only crashes the engine when I try to replace with empty text.
• When I select some text, open the replace menu, try to replace all with a non-empty text, it only replaces the first item. Not sure if this is a separate problem or not.

Steps to reproduce:

1. Select some text in your script.
2. Press Control+R to open the replace menu.
3. Find a text that's in your selection, and press "Replace All" to replace them with empty text.

Minimal reproduction project:

[ThakeeNathees]

Fixed: #37447

[VedatGunel]

Didn't think of checking merged PRs. Thanks for the fix!