Fix \Civi\Token\TokenRow::customToken() failure if field is not set

[aydun]

Overview

Extracted from #13174 and #12012
Fixes a problem in \Civi\Token\TokenRow::customToken(). If the field is not set or does not exist, the getValue API call blows up, so use

Before

Calling \Civi\Token\TokenRow::customToken() with a custom field that is not set fails

After

Calling \Civi\Token\TokenRow::customToken() with a custom field that is not set works

[civibot]

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[mattwire]

getvalue will fail if the (custom) field does not exist. For tokens we don't want to abort, just skip that token and continue. So this is doing the right thing by switching to getsingle.

@aydun Are you sure that all entity APIs will return the custom fields without specifying them in the return? getsingle won't fail if the customfield name is specified in the return but does not exist.

[aydun]

@mattwire Many thanks for reviewing all these changes. Not sure I understand your comment on this one since it does specify the custom field in return. I don't know whether all entities would return the custom fields without specifying them but it seems safer and more performant to specify it. If the field is not returned by getsingle for any reason then $fieldValue is set to the empty string.

[mattwire]

@aydun. Yes I'm sorry! I missed the 'return' => line... So my suggestion was that you add what is already there to make sure it works...

@eileenmcnaughton @seamuslee001 This is ok to merge from my perspective.

[aydun]

@mattwire Thanks!

[seamuslee001]

Merging as per review from Matt