Error filePath.replace is not a function

[mikeKane]

When using this code I get the following error:

TypeError: filePath.replace is not a function
    at StorageReference.putFile (reference.js:101)
    at SubmitPhoto.js:142
    at tryCallOne (core.js:37)
    at core.js:123
    at JSTimers.js:289
    at _callTimer (JSTimers.js:146)
    at _callImmediatesPass (JSTimers.js:194)
    at Object.callImmediates (JSTimers.js:458)
    at MessageQueue.__callImmediates (MessageQueue.js:366)
    at MessageQueue.js:135

Any ideas?