E-notice fix on serialized setting

[eileenmcnaughton]

Overview

E-notice fix on serialized setting

Before

E-notice when using the setting page trait to render a settings form in an extension with a serialized field and declaring field defaults as an array

After

poof

Technical Details

We do actually support settings declaring defaults for a serialized field as an array rather
than as a serialised string. However, this setting form, if used, will display an
e-notice in that case as it will still try to unserialize - this adds a simple check first

Comments

[civibot]

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[seamuslee001]

This looks fine to me