use typeforce >= 1.6.2 which allows us to use `typeforce.TfTypeError` with a custom error message.

package.json

@@ -69,7 +69,7 @@
     "create-hmac": "^1.1.3",
     "ecurve": "^1.0.0",
     "randombytes": "^2.0.1",
-    "typeforce": "^1.5.5",
+    "typeforce": "^1.6.2",
     "wif": "^1.1.0"
   },
   "devDependencies": {

src/types.js

@@ -2,7 +2,8 @@ var typeforce = require('typeforce')
 
 function nBuffer (value, n) {
   typeforce(types.Buffer, value)
-  if (value.length !== n) throw new Error('Expected ' + (n * 8) + '-bit Buffer, got ' + (value.length * 8) + '-bit Buffer')
+  if (value.length !== n) throw new typeforce.TfTypeError('Expected ' + (n * 8) + '-bit Buffer, got ' + (value.length * 8) + '-bit Buffer')
+
   return true
 }
 

test/types.js

@@ -26,14 +26,14 @@ describe('types', function () {
       assert(types.Hash256bit(buffer32byte))
     })
 
-    it('return false for incorrect size', function () {
+    it('throws for incorrect size', function () {
       assert.throws(function () {
         types.Hash160bit(buffer32byte)
-      }, 'Expected 160-bit Buffer, got Number 256')
+      }, /Expected 160-bit Buffer, got 256-bit Buffer/)
 
       assert.throws(function () {
         types.Hash256bit(buffer20byte)
-      }, 'Expected 256-bit Buffer, got Number 160')
+      }, /Expected 256-bit Buffer, got 160-bit Buffer/)
     })
 
     it('return true for oneOf', function () {