fix(core): apply init fields type for fieldArray
fix(core): apply init fields type for fieldArray

ngx-formly/ngx-formly,formly-js/ng2-formly,formly-js/ng2-formly,formly-js/ng-formly,ngx-formly/ngx-formly,formly-js/ng2-formly,formly-js/ng-formly,ngx-formly/ngx-formly,ngx-formly/ngx-formly