From 2a199c39a36cff580067b37b537c31e0862d3703 Mon Sep 17 00:00:00 2001
From: Rodrigo Rodriguez <me@rodrigorodriguez.com>
Date: Tue, 5 Jan 2021 07:47:48 -0300
Subject: [PATCH] fix(basic.gblib): Improving error handling in BASIC.

---
 packages/basic.gblib/services/GBVMService.ts | 20 +++++++++++++++++++-
 src/app.ts                                   |  1 +
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/packages/basic.gblib/services/GBVMService.ts b/packages/basic.gblib/services/GBVMService.ts
index 5285cb2f..1a79b939 100644
--- a/packages/basic.gblib/services/GBVMService.ts
+++ b/packages/basic.gblib/services/GBVMService.ts
@@ -697,15 +697,34 @@ export class GBVMService extends GBService {
     );
   }
 
+  /**
+   * Executes the converted JavaScript from BASIC code inside execution context.
+   */
   public static async callVM(text: string, min: GBMinInstance, step: GBDialogStep, deployer: GBDeployer) {
+    
+    // Creates a class DialogKeywords which is the *this* pointer
+    // in BASIC.
+
     const sandbox: DialogKeywords = new DialogKeywords(min, deployer);
+    
+    // Injects the .gbdialog generated code into the VM.
+    
     const context = vm.createContext(sandbox);
     const code = min.sandBoxMap[text];
     vm.runInContext(code, context);
 
+    // Tries to find the method related to this call.
+
     const mainMethod = text.toLowerCase();
+    if (!sandbox[mainMethod]) {
+      GBLog.error(`BASIC: Associated '${mainMethod}' dialog not found. Verify if .gbdialog is correctly published.`);
+
+      return null;
+    }
     sandbox[mainMethod].bind(sandbox);
 
+    // Calls the function.
+
     let ret = null;
     try {
       ret = await sandbox[mainMethod](step);
@@ -713,7 +732,6 @@ export class GBVMService extends GBService {
     } catch (error) {
       GBLog.error(`BASIC ERROR: ${error.message} ${error.stack}`);
     }
-
     return ret;
   }
 }
diff --git a/src/app.ts b/src/app.ts
index 479f37be..0e5fd67f 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -79,6 +79,7 @@ export class GBServer {
    */
 
   public static run() {
+
     GBLog.info(`The Bot Server is in STARTING mode...`);
     GBServer.globals = new RootData();
     GBConfigService.init();