feat: propagate data.cause as cause in JsonRpcError constructor

src/classes.ts

@@ -2,7 +2,7 @@ import type {
   Json,
   JsonRpcError as SerializedJsonRpcError,
 } from '@metamask/utils';
-import { isPlainObject } from '@metamask/utils';
+import { hasProperty, isObject, isPlainObject } from '@metamask/utils';
 import safeStringify from 'fast-safe-stringify';
 
 import type { OptionalDataWithOptionalCause } from './utils';
@@ -19,6 +19,10 @@ export type { SerializedJsonRpcError };
 export class JsonRpcError<
   Data extends OptionalDataWithOptionalCause,
 > extends Error {
+
+  // This can be removed when tsconfig lib and/or target have changed to >=es2022
+  public cause: OptionalDataWithOptionalCause;
+
   public code: number;
 
   public data?: Data;
@@ -36,6 +40,11 @@ export class JsonRpcError<
     this.code = code;
     if (data !== undefined) {
       this.data = data;
+      if (isObject(data) && hasProperty(data, 'cause')) {
+        this.cause = isObject(data.cause)
+          ? data?.['cause']
+          : undefined;
+      }
     }
   }
 

tsconfig.json

@@ -3,6 +3,7 @@
     "esModuleInterop": true,
     "exactOptionalPropertyTypes": true,
     "forceConsistentCasingInFileNames": true,
+    // Remove custom `cause` field from JsonRpcError when updating
     "lib": ["ES2020"],
     "module": "CommonJS",
     "moduleResolution": "node",