Fix corruption of selected link highlights (#897)

Occurred when deselecting one side of a link when both sides were
selected.

src/LGraph.ts

@@ -919,7 +919,7 @@ export class LGraph implements LinkNetwork, Serialisable<SerialisableGraph> {
   /**
    * Returns a node by its id.
    */
-  getNodeById(id: NodeId): LGraphNode | null {
+  getNodeById(id: NodeId | null | undefined): LGraphNode | null {
     return id != null
       ? this._nodes_by_id[id]
       : null

src/LGraphCanvas.ts

@@ -3365,16 +3365,28 @@ export class LGraphCanvas implements ConnectionColorContext {
 
     this.onNodeDeselected?.(item)
 
+    // Should be moved to top of function, and throw if null
+    const { graph } = this
+    if (!graph) return
+
     // Clear link highlight
     if (item.inputs) {
       for (const input of item.inputs) {
         if (input.link == null) continue
+
+        const node = LLink.getOriginNode(graph, input.link)
+        if (node && this.selectedItems.has(node)) continue
+
         delete this.highlighted_links[input.link]
       }
     }
     if (item.outputs) {
       for (const id of item.outputs.flatMap(x => x.links)) {
         if (id == null) continue
+
+        const node = LLink.getTargetNode(graph, id)
+        if (node && this.selectedItems.has(node)) continue
+
         delete this.highlighted_links[id]
       }
     }

src/LLink.ts

@@ -5,7 +5,7 @@ import type {
   LinkSegment,
   ReadonlyLinkNetwork,
 } from "./interfaces"
-import type { NodeId } from "./LGraphNode"
+import type { LGraphNode, NodeId } from "./LGraphNode"
 import type { Reroute, RerouteId } from "./Reroute"
 import type { Serialisable, SerialisableLLink } from "./types/serialisation"
 
@@ -156,6 +156,28 @@ export class LLink implements LinkSegment, Serialisable<SerialisableLLink> {
       ?.findNextReroute(rerouteId)
   }
 
+  /**
+   * Gets the origin node of a link.
+   * @param network The network to search
+   * @param linkId The ID of the link to get the origin node of
+   * @returns The origin node of the link, or `undefined` if the link is not found or the origin node is not found
+   */
+  static getOriginNode(network: Pick<ReadonlyLinkNetwork, "getNodeById" | "links">, linkId: LinkId): LGraphNode | undefined {
+    const id = network.links.get(linkId)?.origin_id
+    return network.getNodeById(id) ?? undefined
+  }
+
+  /**
+   * Gets the target node of a link.
+   * @param network The network to search
+   * @param linkId The ID of the link to get the target node of
+   * @returns The target node of the link, or `undefined` if the link is not found or the target node is not found
+   */
+  static getTargetNode(network: Pick<ReadonlyLinkNetwork, "getNodeById" | "links">, linkId: LinkId): LGraphNode | undefined {
+    const id = network.links.get(linkId)?.target_id
+    return network.getNodeById(id) ?? undefined
+  }
+
   configure(o: LLink | SerialisedLLinkArray) {
     if (Array.isArray(o)) {
       this.id = o[0]

src/interfaces.ts

@@ -114,7 +114,7 @@ export interface ReadonlyLinkNetwork {
   readonly links: ReadonlyMap<LinkId, LLink>
   readonly reroutes: ReadonlyMap<RerouteId, Reroute>
   readonly floatingLinks: ReadonlyMap<LinkId, LLink>
-  getNodeById(id: NodeId): LGraphNode | null
+  getNodeById(id: NodeId | null | undefined): LGraphNode | null
   getReroute(parentId: null | undefined): undefined
   getReroute(parentId: RerouteId | null | undefined): Reroute | undefined
 }