Uncaught exception `Sys_error("Is a directory")`

[Fakhriddin3040]

I have thoroughly read the Reporting Bugs and Feature Requests wiki page.

#Environment

• Unison version: 2.53.8
• OS: Arch Linux x86_64 (6.19.11-arch1-1)
• CPU: AMD Ryzen 5 4500
• OCaml: 5.4.0
• UI: TUI
• fsmonitor: no

Reproduction Recipe

Just run a command without any options/flags and with tree arguments, and the current directory (.) must be the first argument.

Expected behavior vs actual behavior

Expected behavior: The cli should print the usage or help text in TUI.

Actual behavior: there is an unexpected error, for example command unison . ~ /:

Error: Uncaught exception (please report a bug): Sys_error("Is a directory")
Raised by primitive operation at Stdlib.input_line.scan in file "stdlib.ml", line 453, characters 12-32
Called from Prefs.readAFile.loop in file "/build/unison/src/unison-2.53.8/src/ubase/prefs.ml", line 385, characters 19-36
Called from Prefs.readAFile in file "/build/unison/src/unison-2.53.8/src/ubase/prefs.ml", line 413, characters 10-24
Re-raised at Prefs.readAFile in file "/build/unison/src/unison-2.53.8/src/ubase/prefs.ml", line 413, characters 56-63
Called from Prefs.loadTheFile in file "/build/unison/src/unison-2.53.8/src/ubase/prefs.ml", line 490, characters 27-40
Called from Uicommon.initPrefs in file "/build/unison/src/unison-2.53.8/src/uicommon.ml", line 1037, characters 5-24
Called from Uitext.Body.start in file "/build/unison/src/unison-2.53.8/src/uitext.ml", line 1674, characters 4-78

But when run command unison <not_dot> <arg2> <arg3>, cli printing the usage guide.

P.S: I created current report cause in error was a sentence please report a bug and I thought I can help somehow :).