fix: fix undefined line in branches and functions (#139)

When bundling this [file](https://github.com/browserify/node-util/blob/master/util.js) with esbuild and getting the v8 coverage with playwright `_branchesToIstanbul` and `_functionsToIstanbul` hanged.

These 2 functions actually should throw an error but it is swallowed for some reason.

This PR just ignores if it can't find the source line for the current branch or function.

lib/v8-to-istanbul.js

@@ -257,7 +257,8 @@ module.exports = class V8ToIstanbul {
     }
     this.branches[path] = this.branches[path] || []
     this.branches[path].forEach((branch, index) => {
-      const ignore = source.lines[branch.startLine - 1].ignore
+      const srcLine = source.lines[branch.startLine - 1]
+      const ignore = srcLine === undefined ? true : srcLine.ignore
       branches.branchMap[`${index}`] = branch.toIstanbul()
       branches.b[`${index}`] = [ignore ? 1 : branch.count]
     })
@@ -271,7 +272,8 @@ module.exports = class V8ToIstanbul {
     }
     this.functions[path] = this.functions[path] || []
     this.functions[path].forEach((fn, index) => {
-      const ignore = source.lines[fn.startLine - 1].ignore
+      const srcLine = source.lines[fn.startLine - 1]
+      const ignore = srcLine === undefined ? true : srcLine.ignore
       functions.fnMap[`${index}`] = fn.toIstanbul()
       functions.f[`${index}`] = ignore ? 1 : fn.count
     })