fix: support undefined in hover response per ProviderResult

Author: sqs

src/client/providers/hover.ts

@@ -5,7 +5,9 @@ import { TextDocumentPositionParams, TextDocumentRegistrationOptions } from '../
 import { Hover } from '../../protocol/plainTypes'
 import { FeatureProviderRegistry } from './registry'
 
-export type ProvideTextDocumentHoverSignature = (params: TextDocumentPositionParams) => Observable<Hover | null>
+export type ProvideTextDocumentHoverSignature = (
+    params: TextDocumentPositionParams
+) => Observable<Hover | null | undefined>
 
 /** Provides hovers from all extensions. */
 export class TextDocumentHoverProviderRegistry extends FeatureProviderRegistry<

src/client/types/hover.ts

@@ -9,7 +9,7 @@ export interface HoverMerged {
 
 export namespace HoverMerged {
     /** Create a merged hover from the given individual hovers. */
-    export function from(values: (Hover | PlainHover | null)[]): HoverMerged | null {
+    export function from(values: (Hover | PlainHover | null | undefined)[]): HoverMerged | null {
         const contents: HoverMerged['contents'] = []
         let range: HoverMerged['range']
         for (const result of values) {