Throw an error if using export outside of module

crates/nu-parser/src/errors.rs

@@ -57,6 +57,14 @@ pub enum ParseError {
     #[diagnostic(code(nu::parser::expected_keyword), url(docsrs))]
     ExpectedKeyword(String, #[label("expected {0}")] Span),
 
+    #[error("Unexpected keyword.")]
+    #[diagnostic(
+        code(nu::parser::unexpected_keyword),
+        url(docsrs),
+        help("'export' keyword is allowed only in a module.")
+    )]
+    UnexpectedKeyword(String, #[label("unexpected {0}")] Span),
+
     #[error("Multiple rest params.")]
     #[diagnostic(code(nu::parser::multiple_rest_params), url(docsrs))]
     MultipleRestParams(#[label = "multiple rest params"] Span),

crates/nu-parser/src/parser.rs

@@ -2585,6 +2585,10 @@ pub fn parse_statement(
         b"alias" => parse_alias(working_set, spans),
         b"module" => parse_module(working_set, spans),
         b"use" => parse_use(working_set, spans),
+        b"export" => (
+            garbage_statement(spans),
+            Some(ParseError::UnexpectedKeyword("export".into(), spans[0])),
+        ),
         _ => {
             let (expr, err) = parse_expression(working_set, spans);
             (Statement::Pipeline(Pipeline::from_vec(vec![expr])), err)