Syntax error: Token '.' is an unexpected token

[IJsLauw]

Error: [$parse:syntax] Syntax Error: Token '.' is an unexpected token at column 32 of the expression [caseCtrl.labels.sketch | string.replace:'[steps]':'-1'] starting at [.replace:'[steps]':'-1'].

Any idea why this would break in my project (based on https://github.com/jakemmarsh/angularjs-gulp-browserify-boilerplate)?