Ensure getApplicableRefactors doesn't crash when given a position (#28361)

src/server/session.ts

@@ -1811,7 +1811,7 @@ namespace ts.server {
             return (<protocol.FileLocationRequestArgs>locationOrSpan).line !== undefined;
         }
 
-        private extractPositionAndRange(args: protocol.FileLocationOrRangeRequestArgs, scriptInfo: ScriptInfo): { position: number, textRange: TextRange } {
+        private extractPositionOrRange(args: protocol.FileLocationOrRangeRequestArgs, scriptInfo: ScriptInfo): number | TextRange {
             let position: number | undefined;
             let textRange: TextRange | undefined;
             if (this.isLocation(args)) {
@@ -1821,7 +1821,7 @@ namespace ts.server {
                 const { startPosition, endPosition } = this.getStartAndEndPosition(args, scriptInfo);
                 textRange = { pos: startPosition, end: endPosition };
             }
-            return { position: position!, textRange: textRange! }; // TODO: GH#18217
+            return Debug.assertDefined(position === undefined ? textRange : position);
 
             function getPosition(loc: protocol.FileLocationRequestArgs) {
                 return loc.position !== undefined ? loc.position : scriptInfo.lineOffsetToPosition(loc.line, loc.offset);
@@ -1831,19 +1831,16 @@ namespace ts.server {
         private getApplicableRefactors(args: protocol.GetApplicableRefactorsRequestArgs): protocol.ApplicableRefactorInfo[] {
             const { file, project } = this.getFileAndProject(args);
             const scriptInfo = project.getScriptInfoForNormalizedPath(file)!;
-            const { position, textRange } = this.extractPositionAndRange(args, scriptInfo);
-            return project.getLanguageService().getApplicableRefactors(file, position || textRange, this.getPreferences(file));
+            return project.getLanguageService().getApplicableRefactors(file, this.extractPositionOrRange(args, scriptInfo), this.getPreferences(file));
         }
 
         private getEditsForRefactor(args: protocol.GetEditsForRefactorRequestArgs, simplifiedResult: boolean): RefactorEditInfo | protocol.RefactorEditInfo {
             const { file, project } = this.getFileAndProject(args);
             const scriptInfo = project.getScriptInfoForNormalizedPath(file)!;
-            const { position, textRange } = this.extractPositionAndRange(args, scriptInfo);
-
             const result = project.getLanguageService().getEditsForRefactor(
                 file,
                 this.getFormatOptions(file),
-                position || textRange,
+                this.extractPositionOrRange(args, scriptInfo),
                 args.refactor,
                 args.action,
                 this.getPreferences(file),

src/testRunner/unittests/tsserverProjectSystem.ts

@@ -3433,7 +3433,17 @@ var x = 10;`
                 command: protocol.CommandTypes.GetApplicableRefactors,
                 arguments: { file: file2.path, startLine: 1, startOffset, endLine: 1, endOffset: startOffset + 1 }
             });
+        });
 
+        describe("getApplicableRefactors", () => {
+            it("works when taking position", () => {
+                const aTs: File = { path: "/a.ts", content: "" };
+                const session = createSession(createServerHost([aTs]));
+                openFilesForSession([aTs], session);
+                const response = executeSessionRequest<protocol.GetApplicableRefactorsRequest, protocol.GetApplicableRefactorsResponse>(
+                    session, protocol.CommandTypes.GetApplicableRefactors, { file: aTs.path, line: 1, offset: 1 });
+                assert.deepEqual<ReadonlyArray<protocol.ApplicableRefactorInfo> | undefined>(response, []);
+            });
         });
 
         describe("includes deferred files in the project context", () => {

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -8895,7 +8895,7 @@ declare namespace ts.server {
         private getFullNavigateToItems;
         private getSupportedCodeFixes;
         private isLocation;
-        private extractPositionAndRange;
+        private extractPositionOrRange;
         private getApplicableRefactors;
         private getEditsForRefactor;
         private organizeImports;