extract function, make null check stricter

Author: alxndrsn

packages/node_modules/pouchdb-core/src/adapter.js

@@ -190,6 +190,10 @@ function attachmentNameError(name) {
   return false;
 }
 
+function isNotSingleDoc(doc) {
+  return doc === null || typeof doc !== 'object' || Array.isArray(doc);
+}
+
 function isValidRev(rev) {
   return typeof rev === 'string' && /^\d+-/.test(rev);
 }
@@ -201,7 +205,7 @@ class AbstractPouchDB extends EventEmitter {
         callback = opts;
         opts = {};
       }
-      if (doc == null || typeof doc !== 'object' || Array.isArray(doc)) {
+      if (isNotSingleDoc(doc)) {
         return callback(createError(NOT_AN_OBJECT));
       }
       this.bulkDocs({docs: [doc]}, opts, yankError(callback, doc._id));
@@ -212,7 +216,7 @@ class AbstractPouchDB extends EventEmitter {
         cb = opts;
         opts = {};
       }
-      if (doc == null || typeof doc !== 'object' || Array.isArray(doc)) {
+      if (isNotSingleDoc(doc)) {
         return cb(createError(NOT_AN_OBJECT));
       }
       invalidIdError(doc._id);
@@ -785,7 +789,7 @@ class AbstractPouchDB extends EventEmitter {
       }
 
       for (var i = 0; i < req.docs.length; ++i) {
-        if (req.docs[i] == null || typeof req.docs[i] !== 'object' || Array.isArray(req.docs[i])) {
+        if (isNotSingleDoc(req.docs[i])) {
           return callback(createError(NOT_AN_OBJECT));
         }
       }