chore(core): accept invalid handle id config

Signed-off-by: braks <78412429+bcakmakoglu@users.noreply.github.com>

packages/core/src/utils/edge.ts

@@ -2,7 +2,7 @@ import { isNumber } from '@vueuse/core'
 import type { Actions, EdgePositions, GraphEdge, GraphNode, HandleElement, Rect, ViewportTransform, XYPosition } from '~/types'
 import { Position } from '~/types'
 
-export function getHandlePosition(position: Position, rect: Rect, handle?: HandleElement): XYPosition {
+export function getHandlePosition(position: Position, rect: Rect, handle: HandleElement | null): XYPosition {
   const x = (handle?.x ?? 0) + rect.x
   const y = (handle?.y ?? 0) + rect.y
   const width = handle?.width ?? rect.width
@@ -32,22 +32,26 @@ export function getHandlePosition(position: Position, rect: Rect, handle?: Handl
   }
 }
 
-export function getHandle(bounds: HandleElement[] = [], handleId?: string | null): HandleElement | undefined {
-  if (!bounds.length) return undefined
+export function getHandle(bounds: HandleElement[] = [], handleId?: string | null): HandleElement | null {
+  if (!bounds.length) {
+    return null
+  }
 
-  let handle
-  if (!handleId && bounds.length === 1) handle = bounds[0]
-  else if (handleId) handle = bounds.find((d) => d.id === handleId)
+  if (!handleId || bounds.length === 1) {
+    return bounds[0]
+  } else if (handleId) {
+    return bounds.find((d) => d.id === handleId) || null
+  }
 
-  return handle || bounds[0]
+  return null
 }
 
 export function getEdgePositions(
   sourceNode: GraphNode,
-  sourceHandle: HandleElement | undefined,
+  sourceHandle: HandleElement | null,
   sourcePosition: Position,
   targetNode: GraphNode,
-  targetHandle: HandleElement | undefined,
+  targetHandle: HandleElement | null,
   targetPosition: Position,
 ): EdgePositions {
   const sourceHandlePos = getHandlePosition(