F541 deletes fstring w/o adding additional whitespace

[jasikpark]

With this program:

(""f""r"")
g=""f"{'{:f'}"#

F541 deletes the f in the first fstring and does not add whitespace, producing an invalid doc

thread '<unnamed>' panicked at 'Fixed source has a syntax error where the source document does not. This is a bug in one of the generated fixes:
<filename>:2:16: E999 SyntaxError: unexpected EOF while parsing
  |
1 | (""""r"")
2 | g=""f"{'{:f'}"#
  |                 E999
  |


Last generated fixes:
<filename>:1:4: F541 [*] f-string without any placeholders
  |
1 | (""f""r"")
  |    ^^^ F541
2 | g=""f"{'{:f'}"#
  |
  = help: Remove extraneous `f` prefix

ℹ Fix
1   |-(""f""r"")
  1 |+(""""r"")
2 2 | g=""f"{'{:f'}"#


Source with applied fixes:
(""""r"")
g=""f"{'{:f'}"#'

found via #4822, on main (1c0a3a4)

[charliermarsh]

Thanks! Looks a bit like #4827.

[jasikpark]

indeed!