Vue-meta: metaInfo doesn't have an access to computed properties
vue-meta just creates computed property from your metaInfo function (according to plugin source code), so I assume that your loadViewPage action fills data object asynchronously and your problem just transforms to null-checking problem.
So you should check data before using its properties, and when data will be loaded metaInfo will update object as well:
metaInfo() { // don't know your return object structure, // maybe you should check whole this.getViewPage let data = this.getViewPage.data; return { title: data ? data.meta.title : "some placeholder title", } };