Fix warnings in search_counter

Right now the website breaks if the .json files are missing, or they
contain broken data. Log these cases to see how frequent they are.

Author: flodolo

app/inc/search_counter.php

@@ -3,31 +3,51 @@
 
 use Json\Json;
 
-// Create a JSON file logging locale/number of requests
 $json_data = new Json;
+
+// Create a JSON file logging locale/number of requests
 $local_filename = CACHE_PATH . 'stats_locales.json';
-$stats = $json_data
-    ->setURI($local_filename)
-    ->fetchContent();
+if (file_exists($local_filename)) {
+    $stats = $json_data
+        ->setURI($local_filename)
+        ->fetchContent();
+} else {
+    $stats = [];
+}
+
+// Save JSON only if PHP was able to read the existing stats
+if (is_array($stats)) {
+    $stats[$locale] = array_key_exists($locale, $stats) ? $stats[$locale] += 1 : 1;
+    $json_data->saveFile($stats, $local_filename);
+} else {
+    $logger->addError('stats_locales.json exists but couldn\'t extract a valid array from JSON');
+}
 
-$stats[$locale] = array_key_exists($locale, $stats) ? $stats[$locale] += 1 : 1;
-$json_data->saveFile($stats, $local_filename);
 
 // Create a JSON file logging search options to determine if some are unused
 $local_filename = CACHE_PATH . 'stats_requests.json';
-$stats = $json_data
-    ->setURI($local_filename)
-    ->fetchContent();
+if (file_exists($local_filename)) {
+    $stats = $json_data
+        ->setURI($local_filename)
+        ->fetchContent();
+} else {
+    $stats = [];
+}
 
-foreach ($check as $k => $v) {
-    if (in_array($k, $search->getFormCheckboxes()) && $v == 1) {
-        $stats[$k] = array_key_exists($k, $stats) ? $stats[$k] += 1 : 1;
-    }
+// Save JSON only if PHP was able to read the existing stats
+if (is_array($stats)) {
+    foreach ($check as $k => $v) {
+        if (in_array($k, $search->getFormCheckboxes()) && $v == 1) {
+            $stats[$k] = array_key_exists($k, $stats) ? $stats[$k] += 1 : 1;
+        }
 
-    if (in_array($k, array_diff($search->getFormSearchOptions(), $search->getFormCheckboxes()))) {
-        $stats[$v] = array_key_exists($v, $stats) ? $stats[$v] += 1 : 1;
-    }
+        if (in_array($k, array_diff($search->getFormSearchOptions(), $search->getFormCheckboxes()))) {
+            $stats[$v] = array_key_exists($v, $stats) ? $stats[$v] += 1 : 1;
+        }
 
-    $json_data->saveFile($stats, $local_filename);
+        $json_data->saveFile($stats, $local_filename);
+    }
+} else {
+    $logger->addError('stats_requests.json exists but couldn\'t extract a valid array from JSON');
 }
 unset($stats);