fix(lsp): exit on null root_dir (#15051)

# Description

This PR fixes one reported bug of recent lsp changes.

It exit unexpectedly with empty `root_dir` settings in neovim.

# User-Facing Changes

# Tests + Formatting

+1 test case

# After Submitting

crates/nu-lsp/src/lib.rs

@@ -151,7 +151,7 @@ impl LanguageServer {
                 !self.initial_engine_state.signals().interrupted()
             })
             .into_diagnostic()?;
-        self.initialize_workspace_folders(init_params)?;
+        self.initialize_workspace_folders(init_params);
 
         while !self.initial_engine_state.signals().interrupted() {
             // first check new messages from child thread
@@ -730,7 +730,7 @@ mod tests {
             DidChangeTextDocument, DidOpenTextDocument, Exit, Initialized, Notification,
         },
         request::{Completion, HoverRequest, Initialize, Request, Shutdown},
-        CompletionParams, DidChangeTextDocumentParams, DidOpenTextDocumentParams, InitializeParams,
+        CompletionParams, DidChangeTextDocumentParams, DidOpenTextDocumentParams,
         InitializedParams, PartialResultParams, Position, TextDocumentContentChangeEvent,
         TextDocumentIdentifier, TextDocumentItem, TextDocumentPositionParams,
         WorkDoneProgressParams,
@@ -740,7 +740,7 @@ mod tests {
     use std::time::Duration;
 
     pub(crate) fn initialize_language_server(
-        params: Option<InitializeParams>,
+        params: Option<serde_json::Value>,
     ) -> (Connection, Receiver<Result<()>>) {
         use std::sync::mpsc;
         let (client_connection, server_connection) = Connection::memory();
@@ -757,7 +757,7 @@ mod tests {
             .send(Message::Request(lsp_server::Request {
                 id: 1.into(),
                 method: Initialize::METHOD.to_string(),
-                params: serde_json::to_value(params.unwrap_or_default()).unwrap(),
+                params: params.unwrap_or(serde_json::Value::Null),
             }))
             .unwrap();
         client_connection

crates/nu-lsp/src/workspace.rs

@@ -50,15 +50,14 @@ impl LanguageServer {
     pub(crate) fn initialize_workspace_folders(
         &mut self,
         init_params: serde_json::Value,
-    ) -> Result<()> {
+    ) -> Option<()> {
         if let Some(array) = init_params.get("workspaceFolders") {
-            let folders: Vec<WorkspaceFolder> =
+            let folders: Vec<WorkspaceFolder> = serde_json::from_value(array.clone()).ok()?;
-                serde_json::from_value(array.clone()).into_diagnostic()?;
             for folder in folders {
                 self.workspace_folders.insert(folder.name.clone(), folder);
             }
         }
-        Ok(())
+        Some(())
     }
 
     /// Highlight all occurrences of the text at cursor, in current file
@@ -568,18 +567,36 @@ mod tests {
             .unwrap()
     }
 
+    /// Should not exit on malformed init_params
+    #[test]
+    fn malformed_init_params() {
+        let mut script = fixtures();
+        script.push("lsp");
+        script.push("workspace");
+        let (client_connection, _recv) = initialize_language_server(Some(
+            serde_json::json!({ "workspaceFolders": serde_json::Value::Null }),
+        ));
+        script.push("foo.nu");
+        let script = path_to_uri(&script);
+
+        open_unchecked(&client_connection, script.clone());
+    }
+
     #[test]
     fn command_reference_in_workspace() {
         let mut script = fixtures();
         script.push("lsp");
         script.push("workspace");
-        let (client_connection, _recv) = initialize_language_server(Some(InitializeParams {
+        let (client_connection, _recv) = initialize_language_server(
-            workspace_folders: Some(vec![WorkspaceFolder {
+            serde_json::to_value(InitializeParams {
-                uri: path_to_uri(&script),
+                workspace_folders: Some(vec![WorkspaceFolder {
-                name: "random name".to_string(),
+                    uri: path_to_uri(&script),
-            }]),
+                    name: "random name".to_string(),
-            ..Default::default()
+                }]),
-        }));
+                ..Default::default()
+            })
+            .ok(),
+        );
         script.push("foo.nu");
         let script = path_to_uri(&script);
 
@@ -620,13 +637,16 @@ mod tests {
         let mut script = fixtures();
         script.push("lsp");
         script.push("workspace");
-        let (client_connection, _recv) = initialize_language_server(Some(InitializeParams {
+        let (client_connection, _recv) = initialize_language_server(
-            workspace_folders: Some(vec![WorkspaceFolder {
+            serde_json::to_value(InitializeParams {
-                uri: path_to_uri(&script),
+                workspace_folders: Some(vec![WorkspaceFolder {
-                name: "random name".to_string(),
+                    uri: path_to_uri(&script),
-            }]),
+                    name: "random name".to_string(),
-            ..Default::default()
+                }]),
-        }));
+                ..Default::default()
+            })
+            .ok(),
+        );
         script.push("foo.nu");
         let script = path_to_uri(&script);
 
@@ -667,13 +687,16 @@ mod tests {
         let mut script = fixtures();
         script.push("lsp");
         script.push("workspace");
-        let (client_connection, _recv) = initialize_language_server(Some(InitializeParams {
+        let (client_connection, _recv) = initialize_language_server(
-            workspace_folders: Some(vec![WorkspaceFolder {
+            serde_json::to_value(InitializeParams {
-                uri: path_to_uri(&script),
+                workspace_folders: Some(vec![WorkspaceFolder {
-                name: "random name".to_string(),
+                    uri: path_to_uri(&script),
-            }]),
+                    name: "random name".to_string(),
-            ..Default::default()
+                }]),
-        }));
+                ..Default::default()
+            })
+            .ok(),
+        );
         script.push("foo.nu");
         let script = path_to_uri(&script);
 
@@ -742,13 +765,16 @@ mod tests {
         let mut script = fixtures();
         script.push("lsp");
         script.push("workspace");
-        let (client_connection, _recv) = initialize_language_server(Some(InitializeParams {
+        let (client_connection, _recv) = initialize_language_server(
-            workspace_folders: Some(vec![WorkspaceFolder {
+            serde_json::to_value(InitializeParams {
-                uri: path_to_uri(&script),
+                workspace_folders: Some(vec![WorkspaceFolder {
-                name: "random name".to_string(),
+                    uri: path_to_uri(&script),
-            }]),
+                    name: "random name".to_string(),
-            ..Default::default()
+                }]),
-        }));
+                ..Default::default()
+            })
+            .ok(),
+        );
         script.push("foo.nu");
         let script = path_to_uri(&script);
 
@@ -807,13 +833,16 @@ mod tests {
         let mut script = fixtures();
         script.push("lsp");
         script.push("workspace");
-        let (client_connection, _recv) = initialize_language_server(Some(InitializeParams {
+        let (client_connection, _recv) = initialize_language_server(
-            workspace_folders: Some(vec![WorkspaceFolder {
+            serde_json::to_value(InitializeParams {
-                uri: path_to_uri(&script),
+                workspace_folders: Some(vec![WorkspaceFolder {
-                name: "random name".to_string(),
+                    uri: path_to_uri(&script),
-            }]),
+                    name: "random name".to_string(),
-            ..Default::default()
+                }]),
-        }));
+                ..Default::default()
+            })
+            .ok(),
+        );
         script.push("foo.nu");
         let script = path_to_uri(&script);