Adjust error message format and improve stack traces (#96)

* Adjust error message format and improve stack traces

* Feedback from @mafintosh

* Error constructors are called with different `this`

Author: kasperisager

lib/errors.js

@@ -1,42 +1,50 @@
 module.exports = class HypercoreError extends Error {
-  constructor (msg, code) {
-    super(msg)
+  constructor (msg, code, fn = HypercoreError) {
+    super(`${code}: ${msg}`)
     this.code = code
+
+    if (Error.captureStackTrace) {
+      Error.captureStackTrace(this, fn)
+    }
+  }
+
+  get name () {
+    return 'HypercoreError'
   }
 
   static BAD_ARGUMENT (msg) {
-    return new HypercoreError(msg, 'BAD_ARGUMENT')
+    return new HypercoreError(msg, 'BAD_ARGUMENT', HypercoreError.BAD_ARGUMENT)
   }
 
   static STORAGE_EMPTY (msg) {
-    return new HypercoreError(msg, 'STORAGE_EMPTY')
+    return new HypercoreError(msg, 'STORAGE_EMPTY', HypercoreError.STORAGE_EMPTY)
   }
 
   static STORAGE_CONFLICT (msg) {
-    return new HypercoreError(msg, 'STORAGE_CONFLICT')
+    return new HypercoreError(msg, 'STORAGE_CONFLICT', HypercoreError.STORAGE_CONFLICT)
   }
 
   static INVALID_SIGNATURE (msg) {
-    return new HypercoreError(msg, 'INVALID_SIGNATURE')
+    return new HypercoreError(msg, 'INVALID_SIGNATURE', HypercoreError.INVALID_SIGNATURE)
   }
 
   static INVALID_CAPABILITY (msg) {
-    return new HypercoreError(msg, 'INVALID_CAPABILITY')
+    return new HypercoreError(msg, 'INVALID_CAPABILITY', HypercoreError.INVALID_CAPABILITY)
   }
 
   static SNAPSHOT_NOT_AVAILABLE (msg = 'Snapshot is not available') {
-    return new HypercoreError(msg, 'SNAPSHOT_NOT_AVAILABLE')
+    return new HypercoreError(msg, 'SNAPSHOT_NOT_AVAILABLE', HypercoreError.SNAPSHOT_NOT_AVAILABLE)
   }
 
   static REQUEST_CANCELLED (msg = 'Request was cancelled') {
-    return new HypercoreError(msg, 'REQUEST_CANCELLED')
+    return new HypercoreError(msg, 'REQUEST_CANCELLED', HypercoreError.REQUEST_CANCELLED)
   }
 
   static SESSION_NOT_WRITABLE (msg = 'Session is not writable') {
-    return new HypercoreError(msg, 'SESSION_NOT_WRITABLE')
+    return new HypercoreError(msg, 'SESSION_NOT_WRITABLE', HypercoreError.SESSION_NOT_WRITABLE)
   }
 
   static SESSION_CLOSED (msg = 'Session is closed') {
-    return new HypercoreError(msg, 'SESSION_CLOSED')
+    return new HypercoreError(msg, 'SESSION_CLOSED', HypercoreError.SESSION_CLOSED)
   }
 }