How can I rewrite this?

Suppose you have a simple php array with named keys and integer values that works as expected across many php processes on a site.

for example:

$myArray = array();
$myArray['red'] = 5;
$myArray['blue'] = 3;
$myArray['car'] = 0;
$myArray['apple'] = 10;

However you pass the array to a simple function which causes php to throw a fatal error when trying to access any member of the array.

for example:

function myFunction($input,$myArray)
{
  $count = $myArray['red'] + $myArray['car'];
}

The error produced is:

Fatal error: Uncaught TypeError: Cannot access offset of type string on string in /myFile.php:XX Stack trace: #0 /myFile2.php(XXX): myFunction() #1 {main} thrown in /myFile.php on line XX

The array will print inside the primary function and inside myFunction with print_r($myArray) and each print_r returns the expected result.

for example:

Array ( [red] => 5 [blue] => 3 [car] => 0 [apple] => 10 )

What is causing this problem?

The most similar post found in research is this post.

I have conducted tests before calling myFunction and inside myFunction to understand the array behaviour.

ie. inside mainFunction

  print_r($myArray);
  echo '<p> before:' . $myArray['red'];
  myFunction($input,$myArray);

returns:

before: 5
Array ( [red] => 5 [blue] => 3 [car] => 0 [apple] => 10 )

ie. inside myFunction

  print_r($myArray);
  echo '<p> inside:' . $myArray['red'];

returns:

Fatal error: Uncaught TypeError: Cannot access offset of type string on string in /myFile.php:XX Stack trace: #0 /myFile2.php(XXX): myFunction() #1 {main} thrown in /myFile.php on line XX

Note:
the line echo '<p> inside:' . $myArray['red']; causes the error to throw.