pre 'save' without a callback function fails with unhelpful error message

[ameyanekar]

Do you want to request a feature or report a bug?
bug

What is the current behavior?
Throws an error from the kareem library. Error does not refer to the pre save line of code.

If the current behavior is a bug, please provide the steps to reproduce.

1. Register a pre save hook without any callback: userSchema.pre('save');
2. Execute model.save();

What is the expected behavior?
Error message should be descriptive providing the line of code of the pre save line

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.
Node v10.16.0
mongoose@5.6.9
MongoDB v3.4.18

Complete Error Message Below:

/xxx/xxx/xxx/api-server/node_modules/kareem/index.js:51
    } else if (pre.fn.length > 0) {
                      ^

TypeError: Cannot read property 'length' of undefined
    at model.next (/xxx/api-server/node_modules/kareem/index.js:51:23)
    at _next (/xxx/api-server/node_modules/kareem/index.js:106:10)
    at process.nextTick (/xxx/api-server/node_modules/kareem/index.js:499:38)
    at process._tickCallback (internal/process/next_tick.js:61:11)

[ameyanekar]

Thank you for the swift action @vkarpov15