fix: json error formatter when files are empty

Author: shyim

src/Command/ErrorFormatter/JsonErrorFormatter.php

@@ -60,6 +60,11 @@ public function formatErrors(AnalysisResult $analysisResult, Output $output): in
 			$errorsArray['errors'][] = $notFileSpecificError;
 		}
 
+		// When files empty format it as an empty object
+		if ($errorsArray['files'] === []) {
+			$errorsArray['files'] = new stdClass();
+		}
+
 		$json = Json::encode($errorsArray, $this->pretty ? Json::PRETTY : 0);
 
 		$output->writeRaw($json);

tests/PHPStan/Command/ErrorFormatter/JsonErrorFormatterTest.php

@@ -24,7 +24,7 @@ public function dataFormatterOutputProvider(): iterable
 		"errors":0,
 		"file_errors":0
 	},
-	"files":[],
+	"files":{},
 	"errors": []
 }',
 		];
@@ -67,7 +67,7 @@ public function dataFormatterOutputProvider(): iterable
 		"errors":1,
 		"file_errors":0
 	},
-	"files":[],
+	"files":{},
 	"errors": [
 		"first generic error"
 	]
@@ -133,7 +133,7 @@ public function dataFormatterOutputProvider(): iterable
 		"errors":2,
 		"file_errors":0
 	},
-	"files":[],
+	"files":{},
 	"errors": [
 		"first generic error",
 		"second generic<error>"