Remove unused variant from FormatterError

This seems to be a relic from the change which added external formatting
commands - initially it worked by writing the file in place and
reloading it. Now this error type is not possible and can be removed.

helix-view/src/document.rs

@@ -2198,7 +2198,6 @@ pub enum FormatterError {
     BrokenStdin,
     WaitForOutputFailed,
     InvalidUtf8Output,
-    DiskReloadError(String),
     NonZeroExitStatus(Option<String>),
 }
 
@@ -2213,7 +2212,6 @@ impl Display for FormatterError {
             Self::BrokenStdin => write!(f, "Could not write to formatter stdin"),
             Self::WaitForOutputFailed => write!(f, "Waiting for formatter output failed"),
             Self::InvalidUtf8Output => write!(f, "Invalid UTF-8 formatter output"),
-            Self::DiskReloadError(error) => write!(f, "Error reloading file from disk: {}", error),
             Self::NonZeroExitStatus(Some(output)) => write!(f, "Formatter error: {}", output),
             Self::NonZeroExitStatus(None) => {
                 write!(f, "Formatter exited with non zero exit status")