fix: correcly call 'isEdge' in CellEditorHandler (#286)

`isEdge` is not a model function but rather a function of the cell.

packages/core/src/view/handler/CellEditorHandler.ts

@@ -798,8 +798,7 @@ class CellEditorHandler implements GraphPlugin {
       // Workaround for initial offsetHeight not ready for heading in markup
       if (
         this.autoSize &&
-        // @ts-ignore
-        (this.graph.model.isEdge(state.cell) || state.style.overflow !== 'fill')
+        (state.cell.isEdge() || state.style.overflow !== 'fill')
       ) {
         window.setTimeout(() => {
           this.resize();