image elements within .svg files cause run time crash

[ChristianEdwardPadilla]

An image element within an SVG file parsed with this package was observed to cause crashes at run time with the following stack trace:

_TypeError: Flutter framework
  at FlutterVectorGraphicsListener.onDrawImage	(listener.dart: 773)
  at VectorGraphicsCodec.decode	(vector_graphics_codec.dart: 218)
  at decodeVectorGraphics.process.<anonymous closure>	(listener.dart: 99)
  at <asynchronous gap>	(async)
  at VectorGraphicWidgetState._loadPicture.<anonymous closure> (#2)	(vector_graphics.dart: 369)
  at <asynchronous gap>	(async)
  at VectorGraphicWidgetState._loadAssetBytes.<anonymous closure>	(vector_graphics.dart: 402)
  at <asynchronous gap>	(async)

(internal tracking issue b/368358823)