Add validation in LspCommand::to_lsp + check for inverted ranges (#22731)

#22690 logged errors and flipped the range in this case. Instead it
brings more visibility to the issue to return errors.

Release Notes:

- N/A

crates/language/src/diagnostic_set.rs

@@ -1,4 +1,5 @@
 use crate::{range_to_lsp, Diagnostic};
+use anyhow::Result;
 use collections::HashMap;
 use lsp::LanguageServerId;
 use std::{
@@ -54,16 +55,16 @@ pub struct Summary {
 impl DiagnosticEntry<PointUtf16> {
     /// Returns a raw LSP diagnostic used to provide diagnostic context to LSP
     /// codeAction request
-    pub fn to_lsp_diagnostic_stub(&self) -> lsp::Diagnostic {
+    pub fn to_lsp_diagnostic_stub(&self) -> Result<lsp::Diagnostic> {
         let code = self
             .diagnostic
             .code
             .clone()
             .map(lsp::NumberOrString::String);
 
-        let range = range_to_lsp(self.range.clone());
+        let range = range_to_lsp(self.range.clone())?;
 
-        lsp::Diagnostic {
+        Ok(lsp::Diagnostic {
             code,
             range,
             severity: Some(self.diagnostic.severity),
@@ -71,7 +72,7 @@ impl DiagnosticEntry<PointUtf16> {
             message: self.diagnostic.message.clone(),
             data: self.diagnostic.data.clone(),
             ..Default::default()
-        }
+        })
     }
 }
 

crates/language/src/language.rs

@@ -1849,14 +1849,19 @@ pub fn point_from_lsp(point: lsp::Position) -> Unclipped<PointUtf16> {
     Unclipped(PointUtf16::new(point.line, point.character))
 }
 
-pub fn range_to_lsp(range: Range<PointUtf16>) -> lsp::Range {
-    let mut start = point_to_lsp(range.start);
-    let mut end = point_to_lsp(range.end);
-    if start > end {
-        log::error!("range_to_lsp called with inverted range {start:?}-{end:?}");
-        mem::swap(&mut start, &mut end);
+pub fn range_to_lsp(range: Range<PointUtf16>) -> Result<lsp::Range> {
+    if range.start > range.end {
+        Err(anyhow!(
+            "Inverted range provided to an LSP request: {:?}-{:?}",
+            range.start,
+            range.end
+        ))
+    } else {
+        Ok(lsp::Range {
+            start: point_to_lsp(range.start),
+            end: point_to_lsp(range.end),
+        })
     }
-    lsp::Range { start, end }
 }
 
 pub fn range_from_lsp(range: lsp::Range) -> Range<Unclipped<PointUtf16>> {