Show Micro.blog error message when available

src/networking/ErrorFactory.ts

@@ -0,0 +1,34 @@
+/*
+ * Factory responsible for creating Errors from network responses.
+ */
+export class ErrorFactory {
+
+    // The Micropub specification defines response errors as:
+    //
+    // {
+    //   "error": "invalid_request",
+    //    "error_description": "The post with the requested URL was not found"
+    // }
+    //
+    // This method is responsible for building an Error instance with the
+    // information contained in the response error (if any).
+    public static async makeErrorFromResponse(
+        response: Response
+    ): Promise<Error> {
+        let errorDetails = ''
+
+        const errorResponse = await response.json()
+        const hasError = errorResponse.error
+        const hasDescription = errorResponse.error_description
+
+        if (hasError && hasDescription) {
+            errorDetails = errorResponse.error_description
+        } else if (hasError) {
+            errorDetails = 'Micro.blog error code: ' + errorResponse.error
+        } else {
+            errorDetails = 'Network error: ' + response.status
+        }
+
+        return new Error(errorDetails)
+    }
+}

src/networking/NetworkClient.ts

@@ -1,3 +1,4 @@
+import { ErrorFactory } from '@networking/ErrorFactory'
 import { NetworkRequest } from '@networking/NetworkRequest'
 
 export interface NetworkClientInterface {
@@ -45,7 +46,7 @@ export class NetworkClient implements NetworkClientInterface {
         })
 
         if (!response.ok) {
-            throw new Error('Network error: ' + response.status)
+            throw await ErrorFactory.makeErrorFromResponse(response)
         }
 
         const isSuccess = response.status >= 200 && response.status < 300