Parser should return non-nullable TypeStatement or throw an exception instead

Author: Kirill Nesmeyanov

src/Parser.php

@@ -120,7 +120,7 @@ private function createLexer(array $grammar): Lexer
     /**
      * @psalm-suppress UndefinedAttributeClass : Optional (builtin) attribute usage
      */
-    public function parse(#[Language('PHP')] mixed $source): ?TypeStatement
+    public function parse(#[Language('PHP')] mixed $source): TypeStatement
     {
         $this->lastProcessedTokenOffset = 0;
 
@@ -142,7 +142,10 @@ public function parse(#[Language('PHP')] mixed $source): ?TypeStatement
                     }
                 }
 
-                return null;
+                throw new ParseException(
+                    message: 'Could not read type statement',
+                    code: ParseException::ERROR_CODE_INTERNAL_ERROR,
+                );
             } catch (UnexpectedTokenException $e) {
                 throw $this->unexpectedTokenError($e, $instance);
             } catch (UnrecognizedTokenException $e) {
@@ -161,8 +164,6 @@ public function parse(#[Language('PHP')] mixed $source): ?TypeStatement
                 previous: $e,
             );
         }
-
-        return null;
     }
 
     /**

src/ParserInterface.php

@@ -21,5 +21,5 @@ interface ParserInterface
      *
      * @psalm-suppress UndefinedAttributeClass : Optional (builtin) attribute usage
      */
-    public function parse(#[Language('PHP')] mixed $source): ?TypeStatement;
+    public function parse(#[Language('PHP')] mixed $source): TypeStatement;
 }