feat: don't crash LSP when there are errors resolving the workspace (#6257)

# Description

## Problem

Before this PR, LSP would crash for assumed workspaces (when we can't
find a Nargo.toml) or when there were errors in the Nargo.toml.

## Summary

Now LSP doesn't crash in the above cases:
- for assumed workspaces we don't crash (we used to not crash but I made
some changes in the past that broke this)
- for errors in Nargo.toml we now output to STDERR, so you can see the
error in the output. This is what Rust Analyzer does, except that they
also have a "rust-analyzer" thing at the bottom that becomes yellow when
there's an error... I didn't implement this (it probably requires some
code on the extension side) but I think if something doesn't work you'd
check the logs or ask, and it's worse if it crashes.

## Additional Context

## Documentation

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

Author: asterite

tooling/lsp/src/lib.rs

@@ -267,12 +267,16 @@ fn byte_span_to_range<'a, F: files::Files<'a> + ?Sized>(
 
 pub(crate) fn resolve_workspace_for_source_path(file_path: &Path) -> Result<Workspace, LspError> {
     if let Some(toml_path) = find_file_manifest(file_path) {
-        return resolve_workspace_from_toml(
+        match resolve_workspace_from_toml(
             &toml_path,
             PackageSelection::All,
             Some(NOIR_ARTIFACT_VERSION_STRING.to_string()),
-        )
-        .map_err(|err| LspError::WorkspaceResolutionError(err.to_string()));
+        ) {
+            Ok(workspace) => return Ok(workspace),
+            Err(error) => {
+                eprintln!("Error while processing {:?}: {}", toml_path, error);
+            }
+        }
     }
 
     let Some(parent_folder) = file_path
@@ -285,14 +289,22 @@ pub(crate) fn resolve_workspace_for_source_path(file_path: &Path) -> Result<Work
             file_path
         )));
     };
+
+    let crate_name = match CrateName::from_str(parent_folder) {
+        Ok(name) => name,
+        Err(error) => {
+            eprintln!("{}", error);
+            CrateName::from_str("root").unwrap()
+        }
+    };
+
     let assumed_package = Package {
         version: None,
         compiler_required_version: Some(NOIR_ARTIFACT_VERSION_STRING.to_string()),
         root_dir: PathBuf::from(parent_folder),
         package_type: PackageType::Binary,
         entry_path: PathBuf::from(file_path),
-        name: CrateName::from_str(parent_folder)
-            .map_err(|err| LspError::WorkspaceResolutionError(err.to_string()))?,
+        name: crate_name,
         dependencies: BTreeMap::new(),
         expression_width: None,
     };
@@ -309,7 +321,11 @@ pub(crate) fn workspace_package_for_file<'a>(
     workspace: &'a Workspace,
     file_path: &Path,
 ) -> Option<&'a Package> {
-    workspace.members.iter().find(|package| file_path.starts_with(&package.root_dir))
+    if workspace.is_assumed {
+        workspace.members.first()
+    } else {
+        workspace.members.iter().find(|package| file_path.starts_with(&package.root_dir))
+    }
 }
 
 pub(crate) fn prepare_package<'file_manager, 'parsed_files>(