fix(Slack Node): Do not try to parse block if it's already object (#9643)

Co-authored-by: कारतोफ्फेलस्क्रिप्ट™ <aditya@netroy.in>

packages/core/test/NodeExecuteFunctions.test.ts

@@ -2,6 +2,7 @@ import type { SecureContextOptions } from 'tls';
 import {
 	cleanupParameterData,
 	copyInputItems,
+	ensureType,
 	getBinaryDataBuffer,
 	parseIncomingMessage,
 	parseRequestObject,
@@ -25,6 +26,7 @@ import type {
 	Workflow,
 	WorkflowHooks,
 } from 'n8n-workflow';
+import { ExpressionError } from 'n8n-workflow';
 import { BinaryDataService } from '@/BinaryData/BinaryData.service';
 import nock from 'nock';
 import { tmpdir } from 'os';
@@ -583,4 +585,81 @@ describe('NodeExecuteFunctions', () => {
 			},
 		);
 	});
+
+	describe('ensureType', () => {
+		it('throws error for null value', () => {
+			expect(() => ensureType('string', null, 'myParam')).toThrowError(
+				new ExpressionError("Parameter 'myParam' must not be null"),
+			);
+		});
+
+		it('throws error for undefined value', () => {
+			expect(() => ensureType('string', undefined, 'myParam')).toThrowError(
+				new ExpressionError("Parameter 'myParam' could not be 'undefined'"),
+			);
+		});
+
+		it('returns string value without modification', () => {
+			const value = 'hello';
+			const expectedValue = value;
+			const result = ensureType('string', value, 'myParam');
+			expect(result).toBe(expectedValue);
+		});
+
+		it('returns number value without modification', () => {
+			const value = 42;
+			const expectedValue = value;
+			const result = ensureType('number', value, 'myParam');
+			expect(result).toBe(expectedValue);
+		});
+
+		it('returns boolean value without modification', () => {
+			const value = true;
+			const expectedValue = value;
+			const result = ensureType('boolean', value, 'myParam');
+			expect(result).toBe(expectedValue);
+		});
+
+		it('converts object to string if toType is string', () => {
+			const value = { name: 'John' };
+			const expectedValue = JSON.stringify(value);
+			const result = ensureType('string', value, 'myParam');
+			expect(result).toBe(expectedValue);
+		});
+
+		it('converts string to number if toType is number', () => {
+			const value = '10';
+			const expectedValue = 10;
+			const result = ensureType('number', value, 'myParam');
+			expect(result).toBe(expectedValue);
+		});
+
+		it('throws error for invalid conversion to number', () => {
+			const value = 'invalid';
+			expect(() => ensureType('number', value, 'myParam')).toThrowError(
+				new ExpressionError("Parameter 'myParam' must be a number, but we got 'invalid'"),
+			);
+		});
+
+		it('parses valid JSON string to object if toType is object', () => {
+			const value = '{"name": "Alice"}';
+			const expectedValue = JSON.parse(value);
+			const result = ensureType('object', value, 'myParam');
+			expect(result).toEqual(expectedValue);
+		});
+
+		it('throws error for invalid JSON string to object conversion', () => {
+			const value = 'invalid_json';
+			expect(() => ensureType('object', value, 'myParam')).toThrowError(
+				new ExpressionError("Parameter 'myParam' could not be parsed"),
+			);
+		});
+
+		it('throws error for non-array value if toType is array', () => {
+			const value = { name: 'Alice' };
+			expect(() => ensureType('array', value, 'myParam')).toThrowError(
+				new ExpressionError("Parameter 'myParam' must be an array, but we got object"),
+			);
+		});
+	});
 });