Implement toJSON for ArangoError/HttpError

Fixes #632.

Author: pluma

CHANGELOG.md

@@ -16,6 +16,15 @@ This driver uses semantic versioning:
 
 ## [Unreleased]
 
+### Added
+
+- Implemented `toJSON` methods for `ArangoError` and `HttpError`
+
+  This prevents an error where `JSON.stringify` would reliably throw if passed
+  an instance of either of these error types generated by arangojs. Note that
+  you may still want to implement your own JSON representation logic as system
+  errors (e.g. `ECONNREFUSED`) are not wrapped by arangojs and thrown as-is.
+
 ### Fixed
 
 - Stack traces are now improved for most errors when using `precaptureStackTraces`

src/error.ts

@@ -155,6 +155,15 @@ export class ArangoError extends ExtendableError {
   get isArangoError(): true {
     return true;
   }
+
+  toJSON() {
+    return {
+      error: true,
+      errorMessage: this.message,
+      errorNum: this.errorNum,
+      code: this.code,
+    };
+  }
 }
 
 /**
@@ -186,4 +195,11 @@ export class HttpError extends ExtendableError {
       if (err[key]) this[key] = err[key]!;
     }
   }
+
+  toJSON() {
+    return {
+      error: true,
+      code: this.code,
+    };
+  }
 }