Fix panic if tokens are placed after a redirection (#14035)

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fixes #13835

The `concat` function from `span.rs` assumes that two consecutive span
intervals must overlap. But when parsing `let` and `mut` expressions, we
call `parts_including_redirection` which chains two slices of span and
leads to the above condition not holding. So my solution here is to sort
them after chaining.


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Author: Kither12

crates/nu-parser/src/lite_parser.rs

@@ -136,11 +136,15 @@ impl LiteCommand {
     }
 
     pub fn parts_including_redirection(&self) -> impl Iterator<Item = Span> + '_ {
-        self.parts.iter().copied().chain(
-            self.redirection
-                .iter()
-                .flat_map(|redirection| redirection.spans()),
-        )
+        self.parts
+            .iter()
+            .copied()
+            .chain(
+                self.redirection
+                    .iter()
+                    .flat_map(|redirection| redirection.spans()),
+            )
+            .sorted_unstable_by_key(|a| (a.start, a.end))
     }
 }
 

crates/nu-parser/tests/test_parser.rs

@@ -1243,6 +1243,18 @@ fn test_nothing_comparison_eq() {
     assert!(matches!(&element.expr.expr, Expr::BinaryOp(..)));
 }
 
+#[rstest]
+#[case(b"let a o> file = 1")]
+#[case(b"mut a o> file = 1")]
+fn test_redirection_inside_letmut_no_panic(#[case] phase: &[u8]) {
+    let engine_state = EngineState::new();
+    let mut working_set = StateWorkingSet::new(&engine_state);
+    working_set.add_decl(Box::new(Let));
+    working_set.add_decl(Box::new(Mut));
+
+    parse(&mut working_set, None, phase, true);
+}
+
 #[rstest]
 #[case(b"let a = 1 err> /dev/null")]
 #[case(b"let a = 1 out> /dev/null")]