this.importCache[importPath] = defineCall(this, DataTypes); code example

Example: defineCall is not a function at Sequelize.import sequelize.js

//BASICALLY DON'T ADD EMPTY FILES TO YOUR MODELS FOLDER

/* I experienced this issue, the reason was because I added a file on my models directory 
that is not a model, just some code that's meant to do some stuff. 
I suppose we can only add model files on the models directory, 
as index.js checks every file in the whole directory. */