JavaScript is one of the most preferred programming languages for web development and many novice programmers use it for learning programming through web development. JavaScript programmers often rely on browser devTools to debug their programs. The error messages in web browsers get logged into the web console, which is a part of the devTools. However, novice programmers often find it difficult to understand and interpret the error messages. Therefore, we propose JestViz, a tool aimed at helping novice web developers through the modification of the error reporting mechanism and visualization of the stack trace from error messages as a function call graph. We conjecture that these improvements provide novice programmers with a better interpretation of program errors, leading to faster debugging. Our evaluation of JestViz with 20 novice programmers involving the task of comprehending and debugging an erroneous JavaScript program showed that those who used JestViz took 46% lesser time to debug the program and gained an improved understanding of the inputs and nested function calls that produced the errors.