Fixes #20527

src/services/codefixes/inferFromUsage.ts

@@ -71,6 +71,10 @@ namespace ts.codefix {
         }
 
         const containingFunction = getContainingFunction(token);
+        if (containingFunction === undefined) {
+            // Possible in certain syntax error cases
+            return undefined;
+        }
         switch (errorCode) {
             // Variable and Property declarations
             case Diagnostics.Member_0_implicitly_has_an_1_type.code:

tests/cases/fourslash/incompleteFunctionCallCodefix3.ts

@@ -0,0 +1,7 @@
+/// <reference path='fourslash.ts' />
+
+// @noImplicitAny: true
+//// function ...q) {}} f(10);
+
+verify.not.codeFixAvailable([]);
+