fix: out of bounds error, closes [#8]

use .is_some() and if let Some() to make sure that container indexes are still valid, without can cause out of bounds issue due to docker update frequencies

src/app_data/mod.rs

@@ -304,10 +304,12 @@ impl AppData {
                 if self.containers.state.selected().is_some() {
                     self.containers.previous();
                 }
-                // docker rm -f $(docker ps -aq) will cause this to crash
+				// Check is some, else can cause out of bounds error, if containers get removed before a docker update
+                if self.containers.items.get(index).is_some() {
                     self.containers.items.remove(index);
                 }
             }
+        }
 
         for i in containers.iter() {
             if let Some(id) = i.id.as_ref() {

src/ui/draw_blocks.rs

@@ -265,7 +265,10 @@ pub fn draw_chart<B: Backend>(
             .direction(Direction::Horizontal)
             .constraints([Constraint::Percentage(50), Constraint::Percentage(50)].as_ref())
             .split(area);
-        let (cpu, mem) = app_data.lock().containers.items[index].get_chart_data();
+
+		// Check is some, else can cause out of bounds error, if containers get removed before a docker update
+        if let Some(data) = app_data.lock().containers.items.get(index) {
+            let (cpu, mem) = data.get_chart_data();
 
             let cpu_dataset = vec![Dataset::default()
                 .marker(symbols::Marker::Dot)
@@ -296,6 +299,7 @@ pub fn draw_chart<B: Backend>(
             f.render_widget(cpu_chart, area[0]);
             f.render_widget(mem_chart, area[1]);
         }
+    }
 }
 
 /// Create charts