feat: add documentation link in error message (#667)

Author: jsoref

src/fetch-wrapper.ts

@@ -176,13 +176,22 @@ async function getResponseData(response: Response) {
 function toErrorMessage(data: any) {
   if (typeof data === "string") return data;
 
+  let suffix: string;
+
+  // istanbul ignore else - just in case
+  if ("documentation_url" in data) {
+    suffix = ` - ${data.documentation_url}`;
+  } else {
+    suffix = "";
+  }
+
   // istanbul ignore else - just in case
   if ("message" in data) {
     if (Array.isArray(data.errors)) {
-      return `${data.message}: ${data.errors.map(JSON.stringify).join(", ")}`;
+      return `${data.message}: ${data.errors.map(JSON.stringify).join(", ")}${suffix}`;
     }
 
-    return data.message;
+    return `${data.message}${suffix}`;
   }
 
   // istanbul ignore next - just in case

test/request.test.ts

@@ -809,7 +809,7 @@ x//0u+zd/R/QRUzLOw4N72/Hu+UG6MNt5iDZFCtapRaKt6OvSBwy8w==
       .catch((error) => {
         expect(error).toHaveProperty(
           "message",
-          `Validation failed: "Only organization repositories can have users and team restrictions", {"resource":"Search","field":"q","code":"invalid"}`,
+          `Validation failed: "Only organization repositories can have users and team restrictions", {"resource":"Search","field":"q","code":"invalid"} - https://developer.github.com/v3/repos/branches/#update-branch-protection`,
         );
       });
   });