// ⭐ "if" syntax:// -----------------------------------------------------// ╭──⭐───╮ <---- expecting a "statement"// if (condition) statement;// -----------------------------------------------------// ╭──var──╮ <---- ✅ "var" is a "statement"if (true) var a =1;// ╭── block ──╮ <---- ✅ "block" is a statementif (true) { let b =2 }// -----------------------------------------------------------------// ❗can't use "declaration" when "statement" is expected❗// -----------------------------------------------------------------//// ╭──let──╮ <---- ❌ "let" is a "declaration"❗if (true) let c =2;// ^^^//// ⛔ SyntaxError: // Lexical declaration cannot appear in a single-statement context