Instrument: Move code to create scopes [refactor]

lib/instrument/visitors/function.js

@@ -632,8 +632,21 @@ function instrumentFunction(node, fn, parent, key, paramsBlock, bodyBlock, state
  * @returns {undefined}
  */
 function instrumentFunctionOrClassConstructor(node, fn, paramsBlock, bodyBlock, state) {
-	// NB `bodyBlock` here may actually be params block if is an arrow function with no body.
-	// Sort scopes in ascending order of block ID.
+	// Insert tracker call and block vars (`livepack_scopeId` and `livepack_temp`) into function.
+	// NB: `bodyBlock` here may actually be params block if is an arrow function with no body.
+	const trackerNode = createTrackerCall(fn, state);
+	insertTrackerCodeIntoFunction(fn, node, paramsBlock, bodyBlock, trackerNode, state);
+}
+
+/**
+ * Create tracker call.
+ * Create scopes array, and copy external vars down to parent function.
+ * @param {Object} fn - Function object
+ * @param {Object} state - State object
+ * @returns {Object} - AST node for tracker call
+ */
+function createTrackerCall(fn, state) {
+	// Sort scopes in ascending order of block ID
 	const scopes = [...fn.externalVars].map(([block, vars]) => ({block, vars}))
 		.sort((scope1, scope2) => (scope1.block.id > scope2.block.id ? 1 : -1));
 	fn.scopes = scopes;
@@ -650,22 +663,9 @@ function instrumentFunctionOrClassConstructor(node, fn, paramsBlock, bodyBlock,
 		}
 	}
 
-	// Insert tracker call and block vars (`livepack_scopeId` and `livepack_temp`) into function
-	const trackerNode = createTrackerCall(fn.id, scopes, state);
-	insertTrackerCodeIntoFunction(fn, node, paramsBlock, bodyBlock, trackerNode, state);
-}
-
-/**
- * Create tracker call.
- * @param {number} fnId - Function ID
- * @param {Array<Object>} scopes - Array of scope objects in ascending order of block ID
- * @param {Object} state - State object
- * @returns {Object} - AST node for tracker call
- */
-function createTrackerCall(fnId, scopes, state) {
-	// `livepack_tracker(livepack_getFnInfo_3, () => [[livepack_scopeId_2, x]]);`
+	// `livepack_tracker(livepack_getFnInfo_3, () => [[livepack_scopeId_2, x]])`
 	return t.callExpression(state.trackerVarNode, [
-		createFnInfoVarNode(fnId, state),
+		createFnInfoVarNode(fn.id, state),
 		t.arrowFunctionExpression([], t.arrayExpression(
 			scopes.map(scope => t.arrayExpression([
 				scope.block.varsBlock.scopeIdVarNode,