Catch all json-encode errors

Author: johnstevenson

docs/document.md

@@ -165,10 +165,10 @@ Removes empty objects and arrays from the data. If *$order* is true and a schema
 function re-orders the data using the schema content.
 
 ### toJson
-string **toJson** ( bool `$pretty` )
+?string **toJson** ( bool `$pretty` )
 
 Returns a json-encoded string of `$document->data`. If *$pretty* is true, the output will be
-pretty-printed.
+pretty-printed. Returns null on failure with the error in `$document->getError()`.
 
 *Back to:* [Contents](#contents)
 

docs/formatter.md

@@ -99,7 +99,6 @@ $data = $formatter->prune($data);
 ```
 
 ### toJson
-mixed **toJson** ( mixed `$data`, bool `$pretty` )
+string **toJson** ( mixed `$data`, int `$options` )
 
-Returns a json-encoded string of *$data*. Forward-slashes are not escaped and UTF-8 characters are
-not encoded. If *$pretty* is true, the output will be *pretty-printed*.
+Returns a json-encoded string of *$data*. Throws a *RuntimeException* on failure.

src/BaseDocument.php

@@ -75,12 +75,19 @@ public function getError(): string
         return $this->error;
     }
 
-    public function toJson(bool $pretty): string
+    public function toJson(bool $pretty): ?string
     {
         $options = JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE;
         $options |= $pretty ? JSON_PRETTY_PRINT : 0;
 
-        return $this->formatter->toJson($this->data, $options);
+        try {
+            $result = $this->formatter->toJson($this->data, $options);
+        } catch (\RuntimeException $e) {
+            $result = null;
+            $this->error = $e->getMessage();
+        }
+
+        return $result;
     }
 
     public function validate(): bool