rector.php: add JsonThrowOnErrorRector rule

Using the JSON_THROW_ON_ERROR flag of `json_encode` ensures that we
throw on error instead of returning false. This is safer, and means we
don't need to check the return value against false.

http://wiki.php.net/rfc/json_throw_on_error
https://github.com/rectorphp/rector/blob/main/docs/rector_rules_overview.md#jsonthrowonerrorrector

rector.php

@@ -2,6 +2,7 @@
 
 use Rector\Config\RectorConfig;
 use Rector\Php53\Rector\FuncCall\DirNameFileConstantToDirConstantRector;
+use Rector\Php73\Rector\FuncCall\JsonThrowOnErrorRector;
 use Rector\Php74\Rector\Assign\NullCoalescingOperatorRector;
 use Rector\Php80\Rector\FuncCall\ClassOnObjectRector;
 use Rector\Php81\Rector\Array_\FirstClassCallableRector;
@@ -13,6 +14,7 @@
 	]);
 	$rectorConfig->importNames(true, false);
 	$rectorConfig->rule(DirNameFileConstantToDirConstantRector::class);
+	$rectorConfig->rule(JsonThrowOnErrorRector::class);
 	$rectorConfig->rule(NullCoalescingOperatorRector::class);
 	$rectorConfig->rule(ClassOnObjectRector::class);
 	$rectorConfig->rule(FirstClassCallableRector::class);

src/htdocs/map_warps.php

@@ -54,7 +54,7 @@
 	$data = json_encode([
 		'nodes' => $nodes,
 		'links' => $links,
-	]);
+	], JSON_THROW_ON_ERROR);
 
 	$template = Template::getInstance();
 	$template->assign('GameName', $game->getName());

src/lib/Default/smr.inc.php

@@ -267,7 +267,7 @@ function handleUserError(string $message): never {
 		$errorHREF = $container->href();
 		// json_encode the HREF as a safety precaution
 		$template = Template::getInstance();
-		$template->addJavascriptForAjax('EVAL', 'location.href = ' . json_encode($errorHREF));
+		$template->addJavascriptForAjax('EVAL', 'location.href = ' . json_encode($errorHREF, JSON_THROW_ON_ERROR));
 	}
 	$container->go();
 }

src/lib/Smr/Template.php

@@ -170,10 +170,7 @@ public function addJavascriptForAjax(string $varName, mixed $obj): string {
 		if (isset($this->ajaxJS[$varName])) {
 			throw new Exception('Trying to set javascript val twice: ' . $varName);
 		}
-		$json = json_encode($obj);
-		if ($json === false) {
-			throw new Exception('Failed to encode to json: ' . $varName);
-		}
+		$json = json_encode($obj, JSON_THROW_ON_ERROR);
 		return $this->ajaxJS[$varName] = $json;
 	}
 
@@ -275,7 +272,7 @@ protected function convertHtmlToAjaxXml(string $str, bool $returnXml): string {
 			}
 		}
 		if ($returnXml && count($this->jsAlerts) > 0) {
-			$js = '<ALERT>' . json_encode($this->jsAlerts) . '</ALERT>';
+			$js = '<ALERT>' . json_encode($this->jsAlerts, JSON_THROW_ON_ERROR) . '</ALERT>';
 		}
 		if (strlen($js) > 0) {
 			$xml .= '<JS>' . $js . '</JS>';

src/templates/Default/engine/Default/includes/EndingJavascript.inc.php

@@ -18,7 +18,7 @@
 }
 
 foreach ($this->jsAlerts as $string) {
-	?>alert(<?php echo json_encode($string); ?>);<?php
+	?>alert(<?php echo json_encode($string, JSON_THROW_ON_ERROR); ?>);<?php
 }
 
 if (!empty($this->listjsInclude)) { ?>