Fix: Resolve Issue with Negative Infinity

Author: kavishsathia

src/tracer/__tests__/tracer_debug.ts

@@ -112,9 +112,7 @@ function h(f, x) {
 // TODO: Check for -Infinity
 test('general', () => {
   const code = `
-  const x = 1;
-  const f = x => x + "";
-  f(2);
+  -Infinity;
   `
   const program = parse(code, { ecmaVersion: 10, locations: true })!
   const steps = getSteps(convert(program), { stepLimit: 200 })

src/tracer/nodes/Expression/UnaryExpression.ts

@@ -41,8 +41,8 @@ export class StepperUnaryExpression implements UnaryExpression, StepperBaseNode
       && (node.argument as Literal).value as number > 0
     ) {
       return new StepperLiteral(
-        - ((node.argument as Literal).value as number),
-        undefined,
+        -((node.argument as Literal).value as number),
+        (-((node.argument as Literal).value as number)).toString(),
         node.leadingComments,
         node.trailingComments,
         node.loc,