fix: throw named error (#21)

* fix: throw named error

To make debugging easier, throw `DNSQueryFailedError` instead of a
generic `AggregateError` when DNS queries fail.

* chore: fix test

Author: achingbrain

src/dns.ts

@@ -1,4 +1,5 @@
 import { CustomProgressEvent } from 'progress-events'
+import { DNSQueryFailedError } from './errors.ts'
 import { defaultResolver } from './resolvers/default.js'
 import { cache } from './utils/cache.js'
 import { getTypes } from './utils/get-types.js'
@@ -83,10 +84,6 @@ export class DNS implements DNSInterface {
       }
     }
 
-    if (errors.length === 1) {
-      throw errors[0]
-    }
-
-    throw new AggregateError(errors, `DNS lookup of ${domain} ${types} failed`)
+    throw new DNSQueryFailedError(errors, `DNS lookup of ${domain} ${types} failed`)
   }
 }

src/errors.ts

@@ -0,0 +1,4 @@
+export class DNSQueryFailedError extends AggregateError {
+  static name = 'DNSQueryFailedError'
+  name = 'DNSQueryFailedError'
+}

test/index.spec.ts

@@ -230,7 +230,10 @@ describe('dns', () => {
       signal: controller.signal
     })
 
-    await expect(result).to.eventually.be.rejectedWith(error)
+    await expect(result).to.eventually.be.rejected()
+      .with.deep.property('errors', [
+        error
+      ])
 
     // only one resolver should have been called
     expect(resolvers.reduce((acc, curr) => acc + curr.callCount, 0)).to.equal(1)