TASK: Add suggestions from code review

Author: mhsdesign

src/Parser/Tokenizer/Tokenizer.php

@@ -139,13 +139,18 @@ private static function string(\Iterator $fragments): \Iterator
                     $buffer->append($fragments->current());
                     $fragments->next();
 
+                    if (!$fragments->valid()) {
+                        throw new \Exception("@TODO: Unexpected end of input");
+                    }
+
                     $buffer->append($fragments->current());
                     $fragments->next();
                     break;
 
                 default:
                     $buffer->append($fragments->current());
                     $fragments->next();
+                    break;
             }
         }
     }
@@ -176,6 +181,11 @@ public static function templateLiteral(\Iterator $fragments): \Iterator
                 case '$':
                     $dollarSignBuffer = Buffer::empty()->append($fragments->current());
                     $fragments->next();
+
+                    if (!$fragments->valid()) {
+                        throw new \Exception("@TODO: Unexpected end of input");
+                    }
+                    
                     $nextFragment = $fragments->current();
 
                     if ($nextFragment->value === '{') {
@@ -189,13 +199,18 @@ public static function templateLiteral(\Iterator $fragments): \Iterator
                     $buffer->append($fragments->current());
                     $fragments->next();
 
+                    if (!$fragments->valid()) {
+                        throw new \Exception("@TODO: Unexpected end of input");
+                    }
+
                     $buffer->append($fragments->current());
                     $fragments->next();
                     break;
 
                 default:
                     $buffer->append($fragments->current());
                     $fragments->next();
+                    break;
             }
         }
     }