So, to answer your question, it looks like your firstChild is an HTMLElement containing any svgatorPlayer.
You are using ?raw to process the svg as a string.
To fix this problem you must follow this answer.
Secondly, reading the documentation provided, you are not using JavaScript with the svg, but rather placing it as a string. That's why your svgatorPlayer is equal to null, because it doesn't exist when the js is not executed. One solution is to execute the svg in v-html, but be aware of the problem of XSS injection.
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<template>
<div v-html="exampleSvg"></div>
<Component :is="animatedSvg" />
</template>