fix: early null check instead of empty array at codeActio provider

Author: ayame113

lib/adapters/code-action-adapter.ts

@@ -39,15 +39,18 @@ export default class CodeActionAdapter {
     editor: TextEditor,
     range: Range,
     diagnostics: atomIde.Diagnostic[]
-  ): Promise<atomIde.CodeAction[]> {
+  ): Promise<atomIde.CodeAction[] | null> {
     if (linterAdapter == null) {
       return []
     }
     assert(serverCapabilities.codeActionProvider, "Must have the textDocument/codeAction capability")
 
     const params = CodeActionAdapter.createCodeActionParams(linterAdapter, editor, range, diagnostics)
     const actions = await connection.codeAction(params)
-    return (actions || []).map((action) => CodeActionAdapter.createCodeAction(action, connection))
+    if (!actions) {
+      return null
+    }
+    return actions.map((action) => CodeActionAdapter.createCodeAction(action, connection))
   }
 
   private static createCodeAction(