Adjust error message for contracts V3 (#3653)

* Adjust error message for contracts V3

* Adjust mock API

packages/api-contract/src/base/Base.ts

@@ -26,6 +26,6 @@ export abstract class Base<ApiType extends ApiTypes> {
     this.registry = this.abi.registry;
     this._decorateMethod = decorateMethod;
 
-    assert(isFunction(api.rx.tx.contracts?.instantiateWithCode), 'You need to connect to a node with a V3 contracts module. Your node does not expose api.tx.contracts.instantiateWithCode on this instance');
+    assert(isFunction(api.tx.contracts?.instantiateWithCode), 'You need to connect to a chain with a runtime with a V3 contracts module. The runtime does not expose api.tx.contracts.instantiateWithCode');
   }
 }

packages/api-contract/src/base/mock.ts

@@ -8,12 +8,10 @@ const registry = new TypeRegistry();
 
 export const mockApi = {
   registry,
-  rx: {
-    tx: {
-      contracts: {
-        instantiateWithCode: (): never => {
-          throw new Error('mock');
-        }
+  tx: {
+    contracts: {
+      instantiateWithCode: (): never => {
+        throw new Error('mock');
       }
     }
   }