Fix panic when exploring empty dictionary (#12860)

- fixes #12841 

# Description
Add boundary checks to ensure that the row and column chosen in
RecordView are not over the length of the possible row and columns. If
we are out of bounds, we default to Value::nothing.

# Tests + Formatting
Tests ran and formatting done

crates/nu-explore/src/views/record/mod.rs

@@ -20,7 +20,7 @@ use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
 use nu_color_config::{get_color_map, StyleComputer};
 use nu_protocol::{
     engine::{EngineState, Stack},
-    Record, Value,
+    Record, Span, Value,
 };
 use ratatui::{layout::Rect, widgets::Block};
 use std::{borrow::Cow, collections::HashMap};
@@ -180,7 +180,11 @@ impl<'a> RecordView<'a> {
             Orientation::Left => (column, row),
         };
 
-        layer.records[row][column].clone()
+        if layer.records.len() > row && layer.records[row].len() > column {
+            layer.records[row][column].clone()
+        } else {
+            Value::nothing(Span::unknown())
+        }
     }
 
     fn create_tablew(&'a self, cfg: ViewConfig<'a>) -> TableW<'a> {