当我把默认的express应用程序推送到heroku时，我会遇到以下错误。我确保使用了最新的heroku-toolbelt等工具，但这似乎是来自heroku方面的错误？有人见过吗？它可以正常推送并按预期运行，但我怀疑这可能会在未来引起问题。
Counting objects: 7, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (4/4), 404 bytes, done.
Total 4 (delta 1), reused 0 (delta 0)
-----> Heroku receiving push
-----> Node.js app detected
/app/slug-compiler/buildpacks/nodejs2/vendor/json/json:425
return runInNewContext("(" + JSON.stringify(datum) + ")" + lookupCode);
^
TypeError: Cannot read property 'node' of undefined
at evalmachine.<anonymous>:1:118
at lookupDatum (/app/slug-compiler/buildpacks/nodejs2/vendor/json/json:425:10)
at Socket.<anonymous> (/app/slug-compiler/buildpacks/nodejs2/vendor/json/json:628:24)
at Socket.emit (events.js:61:17)
at Socket._onReadable (net.js:656:51)
at IOWatcher.onReadable [as callback] (net.js:177:10)
/app/slug-compiler/buildpacks/nodejs2/vendor/json/json:425
return runInNewContext("(" + JSON.stringify(datum) + ")" + lookupCode);
^
TypeError: Cannot read property 'npm' of undefined
at evalmachine.<anonymous>:1:118
at lookupDatum (/app/slug-compiler/buildpacks/nodejs2/vendor/json/json:425:10)
at Socket.<anonymous> (/app/slug-compiler/buildpacks/nodejs2/vendor/json/json:628:24)
at Socket.emit (events.js:61:17)
at Socket._onReadable (net.js:656:51)
at IOWatcher.onReadable [as callback] (net.js:177:10)
-----> Resolving engine versions
Using Node.js version: 0.4.7
Using npm version: 1.0.94
-----> Fetching Node.js binaries
-----> Vendoring node into slug
-----> Installing dependencies with npm
express@2.5.8 /tmp/build_1m5t2ah1oglfb/node_modules/express
connect@1.8.5 /tmp/build_1m5t2ah1oglfb/node_modules/express/node_modules/connect
qs@0.4.2 /tmp/build_1m5t2ah1oglfb/node_modules/express/node_modules/qs
mime@1.2.4 /tmp/build_1m5t2ah1oglfb/node_modules/express/node_modules/mime
formidable@1.0.9 /tmp/build_1m5t2ah1oglfb/node_modules/express/node_modules/connect/node_modules/formidable
mkdirp@0.3.0 /tmp/build_1m5t2ah1oglfb/node_modules/express/node_modules/mkdirp
jade@0.20.3 /tmp/build_1m5t2ah1oglfb/node_modules/jade
commander@0.5.2 /tmp/build_1m5t2ah1oglfb/node_modules/jade/node_modules/commander
mkdirp@0.3.0 /tmp/build_1m5t2ah1oglfb/node_modules/jade/node_modules/mkdirp
Dependencies installed
-----> Discovering process types
Procfile declares types -> web
-----> Compiled slug size is 3.1MB
-----> Launching... done, v7