Mesh : check case mesh was provided with no .material or .geometry set.

[vatro]

"this will most probably never happen" or "it can / will never happen" ?
If in both cases three.js throws an Error (I'm pretty sure it will) at some point, we don't need to do it -> simplify.

svelthree/src/components/Mesh.svelte

Lines 121 to 148 in 8fb54d2

	/** IMPORTANT Executed when / if an instance was provided **on initializiation** -> only once if at all! */
	function on_instance_provided(): void {
	// check if type of provided instance is correct and then do something with it...
	if (mesh.type === "Mesh") {
	if (mesh.geometry) {
	geometry = mesh.geometry
	if (verbose && log_dev) console.debug(...c_dev(c_name, "saved geometry:", { geometry }))
	} else {
	// this will most probably never happen ( TODO when would it?)
	throw new Error("SVELTHREE > Mesh : 'mesh' provided, but has no geometry!")
	}
	if (mesh.material) {
	material = mesh.material as AnyMaterial
	if (verbose && log_dev) console.debug(...c_dev(c_name, "saved material:", { material }))
	} else {
	// this will most probably never happen ( TODO when would it?)
	throw new Error("SVELTHREE > Mesh : 'mesh' provided, but has no material!")
	}
	mesh.userData.initScale = mesh.scale.x
	mesh.userData.svelthreeComponent = self
	} else {
	throw new Error(
	`SVELTHREE > Mesh Error: provided 'mesh' instance has wrong type '${mesh.type}', should be 'Mesh'!`
	)
	}
	}

[vatro]

// NO ERROR
// has default geometry: empty `BufferGeometry`
// has default material: white `BasicMaterial`
const new_mesh = new _Mesh()

// three.js throws Error: `Uncaught (in promise) TypeError: Cannot read properties of null (reading 'morphAttributes')`
const new_mesh = new _Mesh(null, null)

// SVELTHREE throws Error: `Error: SVELTHREE > Mesh : 'mesh' provided, but has no geometry!`
const new_mesh = new _Mesh()
new_mesh.material = null
new_mesh.geometry = null

// SVELTHREE throws Error: `Error: SVELTHREE > Mesh : 'mesh' provided, but has no material!`
const new_mesh = new _Mesh()
new_mesh.material = null

// SVELTHREE throws Error: Error: `SVELTHREE > Mesh Error: provided 'mesh' instance has wrong type 'OrthographicCamera', should be 'Mesh'!`
const new_mesh = new _OrthographicCamera()

Means: it's ok as it is, but remove unsure comments.

[vatro]

resolved, see 3478ee6