Fix shmop error handling

Behavior changed in PHP 8.0.

src/SharedMemoryParcel.php

@@ -377,8 +377,13 @@ private function readSegment(int $offset, int $size): string
  {
  \assert($this->handle !== null);
 
- /** @psalm-suppress InvalidArgument Psalm needs to be updated for ext-shmop using objects. */
- return \shmop_read($this->handle, $offset, $size);
+ try {
+ return \shmop_read($this->handle, $offset, $size);
+ } catch (\ValueError $error) {
+ throw new ParcelException(
+ 'Failed to read from shared memory block: ' . ($error->getMessage() ?? 'unknown error')
+ );
+ }
  }
 
  /**
@@ -392,11 +397,11 @@ private function writeSegment(string $data): void
  {
  \assert($this->handle !== null);
 
- /** @psalm-suppress InvalidArgument Psalm needs to be updated for ext-shmop using objects. */
- if (!\shmop_write($this->handle, $data, 0)) {
-  $error = \error_get_last();
+ try {
+  \shmop_write($this->handle, $data, 0);
+ } catch (\ValueError $error) {
  throw new ParcelException(
- 'Failed to write to shared memory block: ' . ($error['message'] ?? 'unknown error')
+ 'Failed to write to shared memory block: ' . ($error->getMessage() ?? 'unknown error')
  );
  }
  }