Add missing types for the Exception class properties (#1583)

* Convert Exception to a class
* Add node param type declaration
* Test the types

Author: kabirbaidhya

types/index.d.ts

@@ -66,7 +66,6 @@ declare namespace Handlebars {
   export function K(): void;
   export function createFrame(object: any): any;
   export function blockParams(obj: any[], ids: any[]): any[];
-  export function Exception(message: string): void;
   export function log(level: number, obj: any): void;
   export function parse(input: string, options?: ParseOptions): hbs.AST.Program;
   export function parseWithoutProcessing(input: string, options?: ParseOptions): hbs.AST.Program;
@@ -87,6 +86,20 @@ declare namespace Handlebars {
 
   export function noConflict(): typeof Handlebars;
 
+  export class Exception {
+      constructor(message: string, node?: hbs.AST.Node);
+      description: string;
+      fileName: string;
+      lineNumber?: any;
+      endLineNumber?: any;
+      message: string;
+      name: string;
+      number: number;
+      stack?: string;
+      column?: any;
+      endColumn?: any;
+  }
+
   export class SafeString {
       constructor(str: string);
       toString(): string;

types/test.ts

@@ -201,3 +201,42 @@ function testParseWithoutProcessing() {
 
   const parsedTemplateWithoutOptions: hbs.AST.Program = Handlebars.parseWithoutProcessing('<p>Hello, my name is {{name}}.</p>');
 }
+
+function testExceptionTypings() {
+  // Test exception constructor with a single argument - message.
+  let exception: Handlebars.Exception = new Handlebars.Exception('message');
+
+  // Fields
+  let message: string = exception.message;
+  let lineNumber: number = exception.lineNumber;
+  let column: number = exception.column;
+  let endLineNumber: number = exception.endLineNumber;
+  let endColumn: number = exception.endColumn;
+  let description = exception.description;
+  let name: string = exception.name;
+  let fileName: string = exception.fileName;
+  let stack: string | undefined = exception.stack;
+}
+
+function testExceptionWithNodeTypings() {
+  // Test exception constructor with both arguments.
+  const exception: Handlebars.Exception = new Handlebars.Exception('message', {
+    type: 'MustacheStatement',
+    loc: {
+      source: 'source',
+      start: { line: 1, column: 5 },
+      end: { line: 10, column: 2 }
+    }
+  });
+
+  // Fields
+  let message: string = exception.message;
+  let lineNumber: number = exception.lineNumber;
+  let column: number = exception.column;
+  let endLineNumber: number = exception.endLineNumber;
+  let endColumn: number = exception.endColumn;
+  let description = exception.description;
+  let name: string = exception.name;
+  let fileName: string = exception.fileName;
+  let stack: string | undefined = exception.stack;
+}