When doing the symbol lookup in pest7, I noticed that a non-valid input for symbol (i.e., inputing "asdfafda") would not give a valid warning response. (Not on my computer and not on the staff solution either!). In fact, the yahoo finance csv file output for a non valid symbol would be "{asdfasdf}",N/A,N/A, so I suggest the following fix:
In Line 102 of functions.php
if ($data[2] === "0.00")
should be changed to
if ($data[2] === "N/A")
My guess is that yahoo changed their text output which is not reflected in the distribution code.