In `@src/Migration/Destinations/JSON.php`:
- Around line 173-211: shutdown() currently throws when the source file doesn't
exist, causing failures for empty exports; instead, detect missing $sourcePath
in the shutdown() method and create an empty JSON array file (write "[]") at
$sourcePath (using $this->local and fopen/fwrite or the existing write helpers),
set $this->jsonStarted appropriately, then continue with the transfer logic to
$destPath using $this->local->transfer and the existing device checks
(referencing shutdown(), $this->outputFile, $this->local, $this->deviceForFiles,
$this->directory, $this->jsonStarted, $this->resourceId).

In `@src/Migration/Sources/JSON.php`:
- Around line 123-125: Validate the format of $this->resourceId before
destructuring so you don't create invalid Database/Table objects: check that
$this->resourceId contains a single ':' (e.g. with strpos or explode and count)
and if not throw a clear InvalidArgumentException (include the offending
$this->resourceId in the message). Only proceed to create new Database(...) and
new Table(...) when validation passes; update the code around the [$databaseId,
$tableId] = explode(':', $this->resourceId) line in JSON.php to perform this
check and throw the exception.
- Around line 112-115: The finally block currently unconditionally calls
$this->device->delete($this->filePath) which can remove the user's source file;
change it to only delete the temporary local copy created by downloadToLocal():
track when a download occurred (use the existing $this->downloaded flag) and
delete from the local device used for download instead of $this->device (either
store the Device\Local instance created in downloadToLocal() as a new property
like $this->localDevice or instantiate a local device (Device\Local('/')) in the
finally block) and call $this->localDevice->delete($this->filePath) only when
$this->downloaded is true.

In `@src/Migration/Destinations/JSON.php`:
- Around line 71-74: Add a PHPMD suppression for the unused parameters in the
JSON destination's report() method: update the docblock for the method
JSON::report(array $resources = [], array $resourceIds = []): array to include a
`@SuppressWarnings`("PHPMD.UnusedFormalParameter") (or equivalent PHPMD
annotation) so the unused $resources and $resourceIds do not trigger PHPMD,
keeping the exact signature intact for named-argument compatibility; ensure the
annotation sits in the method-level docblock immediately above the report()
declaration.