Fix crash when there is no header and no data (#78)

Author: Ch00k

src/utils.rs

@@ -50,8 +50,9 @@ pub fn create_list_table<T: Entity>(
             }
         }
     }
-    let id_column = table.get_column_mut(0).unwrap();
-    id_column.set_constraint(ColumnConstraint::MinWidth(ID_COLUMN_WIDTH));
+    if let Some(id_column) = table.get_column_mut(0) {
+        id_column.set_constraint(ColumnConstraint::MinWidth(ID_COLUMN_WIDTH));
+    }
     table
 }
 
@@ -555,6 +556,15 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_create_list_table_no_header_no_data() {
+        let data: Vec<Patient> = vec![];
+        assert_eq!(
+            format_table(create_list_table(data, None, &PATIENTS_LIST_DICOM_TAGS)),
+            ""
+        );
+    }
+
     #[test]
     fn test_create_show_table_patient() {
         let patient = Patient {