Added specific exception for insufficient credit errors

package.json

@@ -1,6 +1,6 @@
 {
     "name": "verifalia",
-    "version": "2.4.0",
+    "version": "2.5.0",
     "description": "Verifalia email validation library for Javascript",
     "homepage": "https://verifalia.com",
     "main": "dist/umd/verifalia.js",

src/MultiplexedRestClient.ts

@@ -7,6 +7,7 @@ import { AuthorizationError } from './errors/AuthorizationError';
 import { WellKnowMimeContentTypes } from './WellKnowMimeContentTypes';
 import { LoggerFactory } from './environments/environment';
 import { RequestThrottledError } from './errors/RequestThrottledError';
+import { InsufficientCreditError } from './errors/InsufficientCreditError';
 
 const loggerFactory = new LoggerFactory();
 const logger = loggerFactory.build('verifalia');
@@ -92,6 +93,12 @@ export class MultiplexedRestClient {
                 throw new AuthorizationError(response.statusText);
             }
 
+            // Payment required
+
+            if (response.status === 402) {
+                throw new InsufficientCreditError();
+            }
+
             // Throttling
 
             if (response.status === 429) {

src/errors/InsufficientCreditError.ts

@@ -0,0 +1,11 @@
+import { VerifaliaError } from "./VerifaliaError";
+
+/**
+ * Thrown when the credit of the requesting account is not enough to accept a given
+ * email validation job.
+ */
+export class InsufficientCreditError extends VerifaliaError {
+    constructor() {
+        super(`The credit of the requesting account is too low to complete the operation.`);
+    }
+}

src/index.ts

@@ -49,4 +49,5 @@ export { AuthorizationError } from './errors/AuthorizationError';
 export { EndpointServerError } from './errors/EndpointServerError';
 export { OperationCancelledError } from './errors/OperationCancelledError';
 export { RequestThrottledError } from './errors/RequestThrottledError';
-export { ServiceUnreachableError } from './errors/ServiceUnreachableError';
+export { ServiceUnreachableError } from './errors/ServiceUnreachableError';
+export { InsufficientCreditError } from './errors/InsufficientCreditError';