script: add fromASM failing test case and fix

src/script.js

@@ -145,6 +145,7 @@ function fromASM (asm) {
   return compile(asm.split(' ').map(function (chunkStr) {
     // opcode?
     if (OPS[chunkStr] !== undefined) return OPS[chunkStr]
+    typeforce(types.Hex, chunkStr)
 
     // data!
     return new Buffer(chunkStr, 'hex')

test/fixtures/script.json

@@ -189,6 +189,12 @@
         "description": "Not enough data: OP_PUSHDATA4 0xffffffff",
         "script": "4effffffff01"
       }
+    ],
+    "fromASM": [
+      {
+        "description": "Expected Hex, got String \"0xff\"",
+        "script": "0xff OP_CHECKSIG"
+      }
     ]
   }
 }

test/script.js

@@ -28,6 +28,14 @@ describe('script', function () {
         assert.strictEqual(bscript.toASM(scriptSig), f.asm)
       })
     })
+
+    fixtures.invalid.fromASM.forEach(function (f) {
+      it('throws ' + f.description, function () {
+        assert.throws(function () {
+          bscript.fromASM(f.script)
+        }, new RegExp(f.description))
+      })
+    })
   })
 
   describe('isPushOnly', function () {