Tab does not indent code

[Sporarum]

Describe the bug

Tab key does not indent selected lines

Scastie snippet link

No response

To Reproduce

1. Write two lines of nonsense
2. Select both
3. Press "tab"
4. "tab" character is added at the end of the selection

Expected behavior

4. Selected lines get indented

Screenshot ( Optional )

No response

Version

Scastie website

What browsers are you seeing the problem on?

Firefox

Relevant log output