Fix TypeError during HTML coverage report when "text" is undefined

[bennycode]

When using the reporter of type "html", then I am getting the following error when creating a code coverage report:

ERROR [coverage]: TypeError: Cannot read property 'text' of undefined
    at D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\report\html.js:288:54
    at Array.forEach (<anonymous>)
    at annotateBranches (D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\report\html.js:255:30)
    at HtmlReport.writeDetailPage (D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\report\html.js:426:9)
    at D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\report\html.js:489:26
    at SyncFileWriter.writeFile (D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\util\file-writer.js:57:9)
    at FileWriter.writeFile (D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\util\file-writer.js:147:23)
    at D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\report\html.js:488:24
    at Array.forEach (<anonymous>)
    at HtmlReport.writeFiles (D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\report\html.js:482:23)
    at D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\report\html.js:484:22
    at Array.forEach (<anonymous>)
    at HtmlReport.writeFiles (D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\report\html.js:482:23)
    at HtmlReport.writeReport (D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\node_modules\istanbul\lib\report\html.js:566:14)
    at writeReport (D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\lib\reporter.js:68:16)
    at D:\dev\projects\bennyn\test-coverage\node_modules\karma-coverage\lib\reporter.js:297:11
Done in 2.93s.

Although the error above is fired, istanbul still creates a HTML report with index files. I can open them but I cannot click on links like this:

http://localhost:63342/test-coverage/coverage/browser/HeadlessChrome%200.0.0%20(Windows%2010%200.0.0)/main/MyClass.ts.html

When checking for the existence of structuredText[startLine], then I mitigate the error and istanbul creates a HTML report for me where I can see details of classes.

I don't know if that is a proper fix because I guess we should find out why structuredText[startLine] is not defined but I wanted to create awareness for this problem. At least this fix creates a coverage report in HTML for me.

[coveralls]

Coverage increased (+0.001%) to 97.524% when pulling 60a1fed on bennyn:patch-1 into bc84c31 on gotwarlost:master.

[motin]

This was already proposed to be fixed in
#819
#816
and
4a5e92c

(None of them merged)

[keenaudio]

Appears to be a conflict with karma-coverage, which will be loaded automatically by karma if it exists under node_modules.

npm uninstall karma-coverage and removing karma-coverage from package.json fixed the issue for me.