fix html serializer called with invalid arguments

lib/serializers/html.js

@@ -9,6 +9,7 @@ import ReactDOMServer from 'react-dom/server'
 import State from '../models/state'
 import Text from '../models/text'
 import cheerio from 'cheerio'
+import typeOf from 'type-of'
 import { Record } from 'immutable'
 
 /**
@@ -133,11 +134,18 @@ class Html {
 
     elements.forEach((element) => {
       const node = this.deserializeElement(element)
-      if (!node) return
-      if (Array.isArray(node)) {
+      switch (typeOf(node)) {
+        case 'array':
           nodes = nodes.concat(node)
-      } else {
+          break
+        case 'object':
           nodes.push(node)
+          break
+        case 'null':
+        case 'undefined':
+          return
+        default:
+          throw new Error(`A rule returned an invalid deserialized representation: "${node}".`)
       }
     })
 
@@ -155,9 +163,17 @@ class Html {
     let node
 
     const next = (elements) => {
-      return Array.isArray(elements)
-        ? this.deserializeElements(elements)
-        : this.deserializeElement(elements)
+      switch (typeOf(elements)) {
+        case 'array':
+          return this.deserializeElements(elements)
+        case 'object':
+          return this.deserializeElement(elements)
+        case 'null':
+        case 'undefined':
+          return
+        default:
+          throw new Error(`The \`next\` argument was called with invalid children: "${elements}".`)
+      }
     }
 
     for (const rule of this.rules) {
@@ -246,6 +262,7 @@ class Html {
       const ret = rule.serialize(node, children)
       if (ret) return addKey(ret)
     }
+
     throw new Error(`No serializer defined for node of type "${node.type}".`)
   }
 
@@ -266,6 +283,7 @@ class Html {
         const ret = rule.serialize(mark, children)
         if (ret) return addKey(ret)
       }
+
       throw new Error(`No serializer defined for mark of type "${mark.type}".`)
     }, text)
   }

test/serializers/fixtures/html/deserialize/no-next/index.js

@@ -0,0 +1,18 @@
+
+export default {
+  rules: [
+    {
+      deserialize(el, next) {
+        switch (el.tagName) {
+          case 'p': {
+            return {
+              kind: 'block',
+              type: 'paragraph',
+              nodes: next(undefined)
+            }
+          }
+        }
+      }
+    }
+  ]
+}

test/serializers/fixtures/html/deserialize/no-next/input.html

@@ -0,0 +1 @@
+<p></p>

test/serializers/fixtures/html/deserialize/no-next/output.yaml

@@ -0,0 +1,7 @@
+
+nodes:
+  - type: paragraph
+    isVoid: false
+    data: {}
+    nodes:
+      - characters: []