Handle strict typing in Checker and fix tests

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/private/IntegrityCheck/Checker.php b/lib/private/IntegrityCheck/Checker.php
index f1a04d0eac4..44544b6770e 100644
--- a/lib/private/IntegrityCheck/Checker.php
+++ b/lib/private/IntegrityCheck/Checker.php
@@ -333,7 +333,12 @@ class Checker {
 			return [];
 		}
 
-		$signatureData = json_decode($this->fileAccessHelper->file_get_contents($signaturePath), true);
+		$content = $this->fileAccessHelper->file_get_contents($signaturePath);
+		$signatureData = null;
+
+		if (\is_string($content)) {
+			$signatureData = json_decode($content, true);
+		}
 		if(!\is_array($signatureData)) {
 			throw new InvalidSignatureException('Signature data not found.');
 		}