lib: refactor source map stack trace prepare

• Make use of the nullish coalescing operator (`??`) for better
readability.
• Remove unnecessary wrapping.

lib/internal/source_map/prepare_stack_trace.js

@@ -89,12 +89,12 @@ const prepareStackTrace = (globalThis, error, trace) => {
  // Construct call site name based on: v8.dev/docs/stack-trace-api:
  const fnName = t.getFunctionName() ?? t.getMethodName();
  const originalName = `${t.getTypeName() !== 'global' ?
- `${t.getTypeName()}.` : ''}${fnName ? fnName : '<anonymous>'}`;
+ `${t.getTypeName()}.` : ''}${fnName ?? '<anonymous>'}`;
  // The original call site may have a different symbol name
  // associated with it, use it:
  const prefix = (name && name !== originalName) ?
  `${name}` :
- `${originalName ? originalName : ''}`;
+ `${originalName ?? ''}`;
  const hasName = !!(name || originalName);
  const originalSourceNoScheme =
  StringPrototypeStartsWith(originalSource, 'file://') ?
@@ -160,7 +160,7 @@ function getErrorSource(
  let prefix = '';
  for (const character of new SafeStringIterator(
  StringPrototypeSlice(line, 0, originalColumn + 1))) {
- prefix += (character === '\t') ? '\t' :
+ prefix += character === '\t' ? '\t' :
  StringPrototypeRepeat(' ', getStringWidth(character));
  }
  prefix = StringPrototypeSlice(prefix, 0, -1); // The last character is '^'.