diff --git a/lib/Data.php b/lib/Data.php
index be17138..2beb496 100644
--- a/lib/Data.php
+++ b/lib/Data.php
@@ -79,16 +79,6 @@ class Data {
             $this->eof = true;
         }
 
-        if (self::$debug) {
-            echo "\nConsume\n==========\n";
-            echo "Length: $length\n";
-            echo "Data: ";
-            var_export($string);
-            echo "\n";
-            echo "Pointer: {$this->data->posChar()}\n";
-            echo "==========\n\n";
-        }
-
         return $string;
     }
 
@@ -111,12 +101,6 @@ class Data {
                 $this->_column -= $length;
             }
         }
-
-        if (self::$debug) {
-            echo "\nUnconsume\n==========\n";
-            echo "Pointer: {$this->data->posChar()}\n";
-            echo "==========\n\n";
-        }
     }
 
     public function consumeWhile(string $match, int $limit = 0): string {
@@ -132,15 +116,6 @@ class Data {
 
         $string = $this->data->peekChar($length);
 
-        if (self::$debug) {
-            echo "\nPeek\n==========\n";
-            echo "Data: ";
-            var_export($string);
-            echo "\n";
-            echo "Pointer: {$this->data->posChar()}\n";
-            echo "==========\n\n";
-        }
-
         return $string;
     }
 
@@ -204,16 +179,6 @@ class Data {
             $this->data->seek(($advancePointer) ? -1 : 0 - $count - 2);
         }
 
-        if (self::$debug) {
-            echo ($advancePointer) ? "\nconsume" : "\npeek";
-            echo ($while) ? 'While' : 'Until';
-            echo "\n==========\nPattern: ";
-            var_export(str_replace(["\t", "\n", "\x0c", "\x0d"], ['\t', '\n', '\x0c', '\x0d'], implode('', $match)));
-            echo "\nData: ";
-            var_export($string);
-            echo "\nPointer: {$this->data->posChar()}\n==========\n\n";
-        }
-
         return $string;
     }
 
diff --git a/lib/ParseErrorEmitter.php b/lib/ParseErrorEmitter.php
index 1b97d8b..b61dd03 100644
--- a/lib/ParseErrorEmitter.php
+++ b/lib/ParseErrorEmitter.php
@@ -8,14 +8,8 @@ trait ParseErrorEmitter {
 
     private function error(int $code, ...$arg): bool {
         $data = ($this instanceof Data) ? $this : ($this->data ?? null);
-        if ($this->errorHandler) {
-            if ($data) {
-                return $this->errorHandler->emit($data->filePath, $data->line, $data->column, $code, ...$arg);
-            } else {
-                throw new \Exception("Emitted parse error without data stream");
-            }
-        } else {
-            throw new \Exception("Emitted error without error handler");
-        }
+        assert($data instanceof Data);
+        assert($this->errorHandler instanceof ParseError);
+        return $this->errorHandler->emit($data->filePath, $data->line, $data->column, $code, ...$arg);
     }
 }
diff --git a/lib/Tokenizer.php b/lib/Tokenizer.php
index 515d810..0daab53 100644
--- a/lib/Tokenizer.php
+++ b/lib/Tokenizer.php
@@ -997,7 +997,8 @@ class Tokenizer {
                 }
                 # Anything else
                 else {
-                    # Switch to the script data state. Reconsume the current input character.
+                    # Switch to the script data state.
+                    # Reconsume the current input character.
                     $this->state = self::SCRIPT_DATA_STATE;
                     $this->data->unconsume();
                 }
@@ -3389,7 +3390,7 @@ class Tokenizer {
 
             # Not a valid state, unimplemented, or implemented elsewhere
             else {
-                throw new \Exception("Unimplemented state: ".(self::STATE_NAMES[$this->state] ?? $this->state));
+                throw new \Exception("Unimplemented state: ".(self::STATE_NAMES[$this->state] ?? $this->state)); // @codeCoverageIgnore
             }
         }
     }
@@ -3635,7 +3636,7 @@ class Tokenizer {
 
                     // OPTIMIZATION: Combine all digit types
                     // NOTE: This branch should never be reached 
-                    $charRefCode = ($charRefCode * 16) + hexdec($char);
+                    $charRefCode = ($charRefCode * 16) + hexdec($char); // @codeCoverageIgnore
                 }
                 # U+003B SEMICOLON
                 elseif ($char === ';') {
@@ -3665,7 +3666,7 @@ class Tokenizer {
 
                     // OPTIMIZATION: Combine all digit types
                     // NOTE: This branch should never be reached 
-                    $charRefCode = ($charRefCode * 10) + ((int) ($char));
+                    $charRefCode = ($charRefCode * 10) + ((int) ($char)); // @codeCoverageIgnore
                 }
                 # U+003B SEMICOLON
                 elseif ($char === ';') {
@@ -3728,7 +3729,7 @@ class Tokenizer {
 
             # Not a valid state, unimplemented, or implemented elsewhere
             else {
-                throw new \Exception("Unimplemented character reference consumption state: ".(self::STATE_NAMES[$this->state] ?? $this->state));
+                throw new \Exception("Unimplemented character reference consumption state: ".(self::STATE_NAMES[$this->state] ?? $this->state)); // @codeCoverageIgnore
             }
         }        
     }
diff --git a/tests/cases/TestTokenizer.php b/tests/cases/TestTokenizer.php
index ba7d0ba..26dea15 100644
--- a/tests/cases/TestTokenizer.php
+++ b/tests/cases/TestTokenizer.php
@@ -8,7 +8,16 @@ use dW\HTML5\OpenElementsStack;
 use dW\HTML5\ParseError;
 use dW\HTML5\Tokenizer;
 
-/** @covers \dW\HTML5\Tokenizer */
+/** 
+ * @covers \dW\HTML5\Tokenizer
+ * @covers \dW\HTML5\Data
+ * @covers \dW\HTML5\CharacterToken
+ * @covers \dW\HTML5\CommentToken
+ * @covers \dW\HTML5\DataToken
+ * @covers \dW\HTML5\TagToken
+ * @covers \dW\HTML5\DOCTYPEToken
+ * @covers \dW\HTML5\TokenAttr
+ */
 class TestTokenizer extends \dW\HTML5\Test\StandardTest {
     const DEBUG = false;