fulfil interface reqs and use const for find result

Author: rerpha

app/wall/utils.test.ts

@@ -29,6 +29,7 @@ test("updateTargetStationBeamCurrent returns new array with beam current of targ
     targetStation: "Target station 123",
     beamCurrentPv: beamCurrPv,
     beamCurrent: 0.0,
+    instruments: [],
   };
   const expectedValue = 3.14159265358979;
   expect(

app/wall/utils.ts

@@ -39,7 +39,7 @@ export function updateTargetStationBeamCurrent(
 ) {
   const newData: Array<targetStation> = [...prev];
 
-  let foundTs = newData.find((ts) => ts.beamCurrentPv === updatedPVName);
+  const foundTs = newData.find((ts) => ts.beamCurrentPv === updatedPVName);
   if (foundTs) {
     foundTs.beamCurrent = updatedPVvalue;
   }