fix: initialize autofocus selection in createView (#2212)

* initialize autofocus selection in `createView`

* fix missing variable and null error

* remove unused imports

packages/core/src/helpers/resolveFocusPosition.ts

@@ -0,0 +1,22 @@
+import { Node as ProseMirrorNode } from 'prosemirror-model'
+import { Selection, TextSelection } from 'prosemirror-state'
+import { FocusPosition } from '../types'
+import minMax from '../utilities/minMax'
+
+export default function resolveFocusPosition(
+  doc: ProseMirrorNode, 
+  position: FocusPosition = null
+): Selection | null {
+
+  if (!position) return null
+  if (position === 'start' || position === true) return Selection.atStart(doc)
+  if (position === 'end') return Selection.atEnd(doc)  
+  if (position === 'all') return TextSelection.create(doc, 0, doc.content.size)
+
+  // Check if `position` is in bounds of the doc if `position` is a number.
+  const minPos = Selection.atStart(doc).from
+  const maxPos = Selection.atEnd(doc).to
+  const resolvedFrom = minMax(position, minPos, maxPos)
+  const resolvedEnd = minMax(position, minPos, maxPos)  
+  return TextSelection.create(doc, resolvedFrom, resolvedEnd)
+}