Fix SelectionRange return type

Author: kjeremy

Cargo.lock

@@ -6,7 +6,7 @@ authors = ["rust-analyzer developers"]
 
 [dependencies]
 crossbeam-channel = "0.4.0"
-lsp-types = { version = "0.72.0", features = ["proposed"] }
+lsp-types = { version = "0.73.0", features = ["proposed"] }
 log = "0.4.8"
 cargo_metadata = "0.9.1"
 serde_json = "1.0.48"

crates/ra_cargo_watch/Cargo.toml

@@ -20,7 +20,7 @@ globset = "0.4.4"
 itertools = "0.8.2"
 jod-thread = "0.1.0"
 log = "0.4.8"
-lsp-types = { version = "0.72.0", features = ["proposed"] }
+lsp-types = { version = "0.73.0", features = ["proposed"] }
 parking_lot = "0.10.0"
 pico-args = "0.3.1"
 rand = { version = "0.7.3", features = ["small_rng"] }

crates/rust-analyzer/Cargo.toml

@@ -85,11 +85,11 @@ pub fn handle_expand_macro(
 pub fn handle_selection_range(
     world: WorldSnapshot,
     params: req::SelectionRangeParams,
-) -> Result<Vec<req::SelectionRange>> {
+) -> Result<Option<Vec<req::SelectionRange>>> {
     let _p = profile("handle_selection_range");
     let file_id = params.text_document.try_conv_with(&world)?;
     let line_index = world.analysis().file_line_index(file_id)?;
-    params
+    let res: Result<Vec<req::SelectionRange>> = params
         .positions
         .into_iter()
         .map_conv_with(&line_index)
@@ -120,7 +120,9 @@ pub fn handle_selection_range(
             }
             Ok(range)
         })
-        .collect()
+        .collect();
+
+    Ok(Some(res?))
 }
 
 pub fn handle_find_matching_brace(