navbar crash from duplicate body-less ambient modules

[DanielRosenwasser]

Repro for #38058

Should be an easy fix.

declare module "foo";
declare module "foo";

<syntax> Response received: navtree (802). Request took 2 ms. Success: false . Message: Error processing request. Cannot read property 'kind' of undefined
TypeError: Cannot read property 'kind' of undefined
    at areSameModule (/home/userDir/built/local/tsserver.js:137217:27)
    at shouldReallyMerge (/home/userDir/built/local/tsserver.js:137199:28)
    at tryMerge (/home/userDir/built/local/tsserver.js:137181:17)
    at /home/userDir/built/local/tsserver.js:137079:25
    at Object.filterMutate (/home/userDir/built/local/tsserver.js:405:17)
    at mergeChildren (/home/userDir/built/local/tsserver.js:137055:16)
    at endNode (/home/userDir/built/local/tsserver.js:136779:17)
    at rootNavigationBarNode (/home/userDir/built/local/tsserver.js:136719:13)
    at Object.getNavigationTree (/home/userDir/built/local/tsserver.js:136683:38)
    at Object.getNavigationTree (/home/userDir/built/local/tsserver.js:160733:37)
    at IOSession.Session.getNavigationTree (/home/userDir/built/local/tsserver.js:172161:44)
    at Session.handlers.ts.Map.ts.getEntries._a.<computed> (/home/userDir/built/local/tsserver.js:170919:61)
    at /home/userDir/built/local/tsserver.js:172625:88
    at IOSession.Session.executeWithRequestId (/home/userDir/built/local/tsserver.js:172616:28)
    at IOSession.Session.executeCommand (/home/userDir/built/local/tsserver.js:172625:33)
    at IOSession.Session.onMessage (/home/userDir/built/local/tsserver.js:172651:35)
    at Interface.<anonymous> (/home/userDir/built/local/tsserver.js:175256:31)
    at Interface.emit (events.js:315:20)
    at Interface._onLine (readline.js:337:10)
    at Interface._normalWrite (readline.js:482:12)
    at Socket.ondata (readline.js:194:10)
    at Socket.emit (events.js:315:20)
    at addChunk (internal/streams/readable.js:309:12)
    at readableAddChunk (internal/streams/readable.js:284:9)
    at Socket.Readable.push (internal/streams/readable.js:223:10)
    at Pipe.onStreamRead (internal/stream_base_commons.js:188:23)

In 4.6.0-dev.20220110, this is tsserver.js:137314:27