Apply phpstan fixes

Author: donatj

src/streams.php

@@ -36,16 +36,16 @@ function faccept( $stream, string ...$accept ) : ?string {
  *
  * The cursor is reset to its original position.
  *
- * @param resource $stream The stream to peek, must be a seekable resource
- * @param int      $length Up to length number of bytes read.
+ * @param resource   $stream The stream to peek, must be a seekable resource
+ * @param int $length Up to length number of bytes read.
  * @return string The peeked string of up to length bytes
  */
 function fpeek( $stream, int $length = 1 ) : string {
 	if( !is_resource($stream) ) {
 		throw new \InvalidArgumentException('Stream must be a resource');
 	}
 
-	$buf = fread($stream, $length);
+	$buf = fread($stream, $length) ?: '';
 	fseek($stream, 0 - strlen($buf), SEEK_CUR);
 
 	return $buf;

test/StreamsTest.php

@@ -32,6 +32,7 @@ public function test_faccept_BOM() : void {
 
 	public function test_faccept_exception() : void {
 		$this->expectException(\InvalidArgumentException::class);
+		// @phpstan-ignore-next-line
 		faccept(123, 'test');
 	}
 
@@ -54,6 +55,7 @@ public function test_fpeek_empty() : void {
 
 	public function test_fpeek_exception() : void {
 		$this->expectException(\InvalidArgumentException::class);
+		// @phpstan-ignore-next-line
 		fpeek(123, 123);
 	}