From d61bafeda3ef5fa2eda89dc03b68e983ad80ece5 Mon Sep 17 00:00:00 2001
From: Bronley Plumb <bronley@gmail.com>
Date: Tue, 28 May 2024 09:54:33 -0400
Subject: [PATCH] Fix crash with optional chaining in signature help (#1207)

---
 src/Program.spec.ts                 | 13 +++++++++++++
 src/bscPlugin/CallExpressionInfo.ts |  9 +++++----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/Program.spec.ts b/src/Program.spec.ts
index 34ebd498d..83184a08e 100644
--- a/src/Program.spec.ts
+++ b/src/Program.spec.ts
@@ -2369,6 +2369,19 @@ describe('Program', () => {
             expect(signatureHelp[0]?.signature).to.not.exist;
         });
 
+        it('does not crash when parts is undefined', () => {
+            program.setFile('source/main.bs', `
+                sub main()
+                    print m.b["c"].hello?(12345)
+                end sub
+            `);
+            program.validate();
+            expectZeroDiagnostics(program);
+            // 123|45
+            let signatureHelp = getSignatureHelp(2, 45);
+            expect(signatureHelp).is.empty;
+        });
+
         describe('gets signature info for regular function call', () => {
             it('does not get help when on method name', () => {
                 program.setFile('source/main.bs', `
diff --git a/src/bscPlugin/CallExpressionInfo.ts b/src/bscPlugin/CallExpressionInfo.ts
index 42c9ecfc7..d1112524d 100644
--- a/src/bscPlugin/CallExpressionInfo.ts
+++ b/src/bscPlugin/CallExpressionInfo.ts
@@ -79,9 +79,11 @@ export class CallExpressionInfo {
 
             } else {
                 let parts = util.getAllDottedGetParts(callExpression.callee);
-                parts.splice(parts?.length - 1, 1);
-                this.dotPart = parts.map(x => x.text).join('.');
-                this.namespace = this.getNamespace();
+                if (parts) {
+                    parts.splice(parts?.length - 1, 1);
+                    this.dotPart = parts.map(x => x.text).join('.');
+                    this.namespace = this.getNamespace();
+                }
             }
         }
 
@@ -162,4 +164,3 @@ export class CallExpressionInfo {
     }
 
 }
-