Handle Mirror Node network fee errors (#240)

* Handle Mirror Node network fee errors

Expand mirror node network fees fallback to encompass all errors
- Add warning log
- Expand test integration capabilities using `sinon`
- Add `eth.spec.ts` coverage for mirror node failures for gas endpoints

Signed-off-by: Nana-EC <[email protected]>

Author: Nana-EC

package-lock.json

@@ -14,6 +14,7 @@
         "@types/mocha": "^9.1.0",
         "@types/node": "^17.0.14",
         "chai": "^4.3.6",
+        "sinon": "^14.0.0",
         "ts-mocha": "^9.0.2",
         "typescript": "^4.6.4"
     },

packages/relay/package.json

@@ -147,10 +147,18 @@ export class EthImpl implements Eth {
   }
 
   private async getFeeWeibars() {
-    let networkFees = await this.mirrorNodeClient.getNetworkFees();
+    let networkFees;
+
+    try {
+      networkFees = await this.mirrorNodeClient.getNetworkFees();
+      if (_.isNil(networkFees)) {
+        this.logger.debug(`Mirror Node returned no fees. Fallback to network`);
+      }
+    } catch (e: any) {
+      this.logger.warn(e, `Mirror Node threw an error retrieving fees. Fallback to network`);
+    }
 
     if (_.isNil(networkFees)) {
-      this.logger.debug(`Mirror Node returned no fees. Fallback to network`);
       networkFees = {
         fees: [
           {
@@ -631,7 +639,7 @@ export class EthImpl implements Eth {
       if (e.status && e.status._code) {
         resolvedError = new Error(e.message);
       }
-      
+
       this.logger.error(resolvedError, 'Failed to successfully submit contractCallQuery');
       return predefined.INTERNAL_ERROR;
     }
@@ -701,7 +709,7 @@ export class EthImpl implements Eth {
 
 
       // support stricter go-eth client which requires the transaction hash property on logs
-      const logs = receiptResponse.logs.map(log => ({ ...log, transactionHash: receiptResponse.hash}));
+      const logs = receiptResponse.logs.map(log => ({ ...log, transactionHash: receiptResponse.hash }));
 
       const receipt = {
         blockHash: receiptResponse.block_hash.substring(0, 66),