Fix fit to content (#841)

* Fix: avoid to select defs or title as parentElement

* Fix: fix problem when nothing is drawing

packages/svgcanvas/utilities.js

@@ -974,6 +974,7 @@ export const getVisibleElements = (parentElement) => {
   }
 
   const contentElems = []
+  if (parentElement) {
     const children = parentElement.children
     // eslint-disable-next-line array-callback-return
     Array.from(children, (elem) => {
@@ -981,6 +982,7 @@ export const getVisibleElements = (parentElement) => {
         contentElems.push(elem)
       }
     })
+  }
   return contentElems.reverse()
 }