LSP: Use negotiated position encoding for workspace edits (#7469)

Previously this was hard-coded to UTF-8 but we might have negotiated
another position encoding.

helix-term/src/application.rs

@@ -1047,9 +1047,12 @@ impl Application {
                         Ok(serde_json::Value::Null)
                     }
                     Ok(MethodCall::ApplyWorkspaceEdit(params)) => {
+                        let language_server = language_server!();
+                        if language_server.is_initialized() {
+                            let offset_encoding = language_server.offset_encoding();
                             let res = apply_workspace_edit(
                                 &mut self.editor,
-                            helix_lsp::OffsetEncoding::Utf8,
+                                offset_encoding,
                                 &params.edit,
                             );
 
@@ -1061,6 +1064,14 @@ impl Application {
                                     .err()
                                     .map(|err| err.failed_change_idx as u32),
                             }))
+                        } else {
+                            Err(helix_lsp::jsonrpc::Error {
+                                code: helix_lsp::jsonrpc::ErrorCode::InvalidRequest,
+                                message: "Server must be initialized to request workspace edits"
+                                    .to_string(),
+                                data: None,
+                            })
+                        }
                     }
                     Ok(MethodCall::WorkspaceFolders) => {
                         Ok(json!(&*language_server!().workspace_folders().await))