extractMethod: Don't try to extract an ExpressionStatement consisting of a single token (#18450)

* extractMethod: Don't try to extract an ExpressionStatement consisting of a single token

* Move to unit test

Author: Andy

src/harness/unittests/extractMethods.ts

@@ -410,6 +410,8 @@ function test(x: number) {
             "Statement or expression expected."
         ]);
 
+        testExtractRangeFailed("extract-method-not-for-token-expression-statement", `[#|a|]`, ["Select more than a single token."]);
+
         testExtractMethod("extractMethod1",
             `namespace A {
     let x = 1;

src/services/refactors/extractMethod.ts

@@ -231,7 +231,7 @@ namespace ts.refactor.extractMethod {
         }
 
         function checkRootNode(node: Node): Diagnostic[] | undefined {
-            if (isToken(node)) {
+            if (isToken(isExpressionStatement(node) ? node.expression : node)) {
                 return [createDiagnosticForNode(node, Messages.InsufficientSelection)];
             }
             return undefined;