Handle the case where the FAR results map is empty (#49254)

* Handle the case where the FAR results map is empty

Searching exactly one project does not imply the presence of exactly one references list.

Fixes #49217

* Use emptyArray

Co-authored-by: Sheetal Nandi <shkamat@microsoft.com>

Co-authored-by: Sheetal Nandi <shkamat@microsoft.com>

Author: amcasey

src/server/session.ts

@@ -575,8 +575,7 @@ namespace ts.server {
         // it easier for the caller to skip post-processing.
         if (searchedProjects.size === 1) {
             const it = resultsMap.values().next();
-            Debug.assert(!it.done);
-            return it.value;
+            return it.done ? emptyArray : it.value; // There may not be any results at all
         }
 
         return resultsMap;

tests/baselines/reference/referenceToEmptyObject.baseline.jsonc

@@ -0,0 +1 @@
+[]

tests/baselines/reference/referencesInEmptyFile.baseline.jsonc

@@ -0,0 +1 @@
+[]

tests/baselines/reference/referencesToStringLiteralValue.baseline.jsonc

@@ -0,0 +1,22 @@
+[
+  {
+    "definition": {
+      "containerKind": "",
+      "containerName": "",
+      "fileName": "/tests/cases/fourslash/server/referencesToStringLiteralValue.ts",
+      "kind": "var",
+      "name": "some  string",
+      "textSpan": {
+        "start": 19,
+        "length": 12
+      },
+      "displayParts": [
+        {
+          "text": "\"some  string\"",
+          "kind": "stringLiteral"
+        }
+      ]
+    },
+    "references": []
+  }
+]

tests/cases/fourslash/server/referenceToEmptyObject.ts

@@ -0,0 +1,5 @@
+/// <reference path='fourslash.ts'/>
+
+////const obj = {}/*1*/;
+
+verify.baselineFindAllReferences('1');

tests/cases/fourslash/server/referencesInEmptyFile.ts

@@ -0,0 +1,5 @@
+/// <reference path='fourslash.ts'/>
+
+/////*1*/
+
+verify.baselineFindAllReferences('1');

tests/cases/fourslash/server/referencesToStringLiteralValue.ts

@@ -0,0 +1,5 @@
+/// <reference path='fourslash.ts'/>
+
+////const s: string = "some /*1*/ string";
+
+verify.baselineFindAllReferences('1');