Add nullable return types and improve exception handling in MotorAPI

- Updated `getCachedResult` methods across `motorapi`, `motorapi_i`, and `motorapi_lookups_o` to return `?object` for nullable results.
- Enhanced error handling in `xlvask_parser_stor_bil` by wrapping `getLicensePlateInformation` in a try-catch block to handle API exceptions gracefully.
- Introduced `cleanJSON` method in `motorapi` to sanitize and validate JSON data, ensuring robust parsing of cached responses.
- Optimized `getCachedResult` logic to handle null and invalid JSON scenarios with detailed error reporting.

services/nginx/app/classes/motorapi.php

@@ -49,6 +49,23 @@ class motorapi implements motorapi_i
         $this->license_plate_lookup = new license_plate_lookup_a();
     }
 
+    private static function cleanJSON(mixed $value): string
+    {
+        if (is_string($value)) {
+            // Remove backslashes
+            $value = stripslashes($value);
+            $value = stripslashes($value);
+            // Ensure the string is valid UTF-8
+            $value = mb_convert_encoding($value, 'UTF-8', 'UTF-8');
+            // Optionally, you can use regex to remove any non-printable characters
+            $value = preg_replace('/[^\x20-\x7E]/', '', $value);
+        } else {
+            echo 'Unable to perform cleaning on value of type ' . gettype($value) . ': ' . print_r($value, true) . PHP_EOL;
+        }
+        // Remove any invalid UTF-8 characters
+        return $value;
+    }
+
     /**
      * Get the recommended products for a license plate
      * @param string $plate The license plate
@@ -109,7 +126,10 @@ class motorapi implements motorapi_i
         // Check if the license plate information is cached
         if (!$ignoreCache && self::isCached($licensePlate)) {
             // Get the cached result
-            return self::getCachedResult($licensePlate);
+            $tmp_res = self::getCachedResult($licensePlate);
+            if ($tmp_res !== null) {
+                return $tmp_res;
+            }
         }
         // Get the license plate information from the motorapi
         return $this->sendRequest($licensePlate, 'vehicles', [], 'GET');
@@ -128,7 +148,7 @@ class motorapi implements motorapi_i
     /**
      * @inheritDoc
      */
-    function getCachedResult(string $licensePlate): object
+    function getCachedResult(string $licensePlate): ?object
     {
         global /** @var response $response */
         $response;
@@ -136,7 +156,13 @@ class motorapi implements motorapi_i
         $motorapi_lookups = new motorapi_lookups_o();
         // Add the cached value to the meta
         $response->add_meta('cached', true);
-        return json_decode($motorapi_lookups->getCachedResult($licensePlate)->result->value());
+        $cleaned_result = self::cleanJSON($motorapi_lookups->getCachedResult($licensePlate)->result->value());
+        $object = json_decode($cleaned_result);
+        if ($object === null) {
+            print_r($cleaned_result);
+            throw new Exception('Cached result is not valid JSON');
+        }
+        return json_decode($cleaned_result);
     }
 
     /**