fix: add type checks for caught errors

web3.js/.eslintignore

@@ -8,4 +8,5 @@
 /.eslintrc.js
 /test/.eslintrc.js
 /test/dist
+/test/rollup.config.js
 /rollup.config.js

web3.js/src/connection.ts

@@ -815,7 +815,7 @@ function createRpcClient(
         callback(new Error(`${res.status} ${res.statusText}: ${text}`));
       }
     } catch (err) {
-      callback(err);
+      if (err instanceof Error) callback(err);
     } finally {
       agentManager && agentManager.requestEnd();
     }
@@ -3260,7 +3260,7 @@ export class Connection {
             block.signatures[block.signatures.length - 1].toString();
         }
       } catch (err) {
-        if (err.message.includes('skipped')) {
+        if (err instanceof Error && err.message.includes('skipped')) {
           continue;
         } else {
           throw err;
@@ -3282,7 +3282,7 @@ export class Connection {
             block.signatures[block.signatures.length - 1].toString();
         }
       } catch (err) {
-        if (err.message.includes('skipped')) {
+        if (err instanceof Error && err.message.includes('skipped')) {
           continue;
         } else {
           throw err;
@@ -3732,7 +3732,13 @@ export class Connection {
           // eslint-disable-next-line require-atomic-updates
           sub.subscriptionId = null;
         }
-        console.error(`${rpcMethod} error for argument`, rpcArgs, err.message);
+        if (err instanceof Error) {
+          console.error(
+            `${rpcMethod} error for argument`,
+            rpcArgs,
+            err.message,
+          );
+        }
       }
     }
   }
@@ -3750,7 +3756,9 @@ export class Connection {
       try {
         await this._rpcWebSocket.call(rpcMethod, [unsubscribeId]);
       } catch (err) {
-        console.error(`${rpcMethod} error:`, err.message);
+        if (err instanceof Error) {
+          console.error(`${rpcMethod} error:`, err.message);
+        }
       }
     }
   }

web3.js/test/mocks/rpc-websockets.ts

@@ -1,6 +1,6 @@
 import {Client as LiveClient} from 'rpc-websockets';
 import {expect} from 'chai';
-import sinon from 'sinon';
+import {createSandbox} from 'sinon';
 
 import {Connection} from '../../src';
 
@@ -17,7 +17,7 @@ type RpcResponse = {
 };
 
 const mockRpcSocket: Array<[RpcRequest, RpcResponse]> = [];
-const sandbox = sinon.createSandbox();
+const sandbox = createSandbox();
 
 export const mockRpcMessage = ({
   method,