fix: define query param depth in Staking Payouts for all chains

[Imod7]

Closes #1421

Description

In #1415 a new variable isKusama was added to ensure that Kusama specific calculations are activated / taking effect only if we are connected to the Kusama chain.
However, with this change the variable sanitizedDepth was left undefined if

• the query param depth had a valid value and
• we were connected to any other chain

The reason is this line of code:

if (depth && isKusama) {
	sanitizedDepth = Math.min(Number(depth), currentEra - 518).toString();
}

where sanitizedDepth is defined only is depth has a value and we are connected to the Kusama chain.

Added a small fix to correct this.