server: Fix script execution error (closes #244)

src/services/backend_script_api.ts

@@ -63,7 +63,7 @@ interface Api {
      * Note where the script started executing (entrypoint).
      * As an analogy, in C this would be the file which contains the main() function of the current process.
      */
-    startNote?: BNote;
+    startNote?: BNote | null;
 
     /**
      * Note where the script is currently executing. This comes into play when your script is spread in multiple code
@@ -76,7 +76,7 @@ interface Api {
     /**
      * Entity whose event triggered this execution
      */
-    originEntity?: AbstractBeccaEntity<any>;
+    originEntity?: AbstractBeccaEntity<any> | null;
     
     /**
      * Axios library for HTTP requests. See {@link https://axios-http.com} for documentation

src/services/backend_script_api_interface.ts

@@ -3,8 +3,8 @@ import AbstractBeccaEntity = require("../becca/entities/abstract_becca_entity");
 import BNote = require("../becca/entities/bnote");
 
 export interface ApiParams {
-    startNote?: BNote;
-    originEntity?: AbstractBeccaEntity<any>;
+    startNote?: BNote | null;
+    originEntity?: AbstractBeccaEntity<any> | null;
     pathParams?: string[],
     req?: Request,
     res?: Response

src/services/script.ts

@@ -95,10 +95,6 @@ function executeScript(script: string, params: ScriptParams, startNoteId: string
         throw new Error("Unable to determine script bundle.");
     }
 
-    if (!startNote || !originEntity) {
-        throw new Error("Missing start note or origin entity.");
-    }
-
     return executeBundle(bundle, { startNote, originEntity });
 }