Final answer:
The error message "Lexical declaration cannot appear in a single-statement context" in JavaScript occurs when you try to declare a variable using 'let' or 'const' in a context where only a single statement is allowed. To fix this error, you need to ensure that the 'let' or 'const' declaration is inside a block of code. Here's an example of the correct usage.
Step-by-step explanation:
This error message, "Lexical declaration cannot appear in a single-statement context," occurs in JavaScript when you try to declare a variable using the let or const keyword in a context where multiple statements are not allowed. For example, you might be trying to declare a variable within a control structure conditional statement without wrapping it in a block of code.
To fix this error, you need to ensure that any let or const declarations are inside a block of code, such as within curly brackets {}. This block of code contains multiple statements and allows for the proper declaration of variables.
Here's an example:
if (condition) {
let x = 10;
const y = 20;
// Rest of the code
}