Decrement file count if browserResult undefined.
Decrement file count if browserResult undefined.

When the karma test units encountered a script error at the start of a test run, onRunComplete was called, but browserResults[browser.id] was undefined.  It would return early, preventing a crash, but never decrement pendingFileWritings, which would cause karma to hang indefinitely and never call done.
briwa/karma-htmlmarkdown-reporter,dtabuenc/karma-html-reporter,dtabuenc/karma-html-reporter,briwa/karma-htmlmarkdown-reporter