Improve some logger error messages.

backend/src/api/bisq/bisq.ts

@@ -133,7 +133,7 @@ class Bisq {
 
   private updatePrice() {
     request('https://markets.bisq.network/api/trades/?market=bsq_btc', { json: true }, (err, res, trades: BisqTrade[]) => {
-      if (err) { return logger.err(err); }
+      if (err) { return logger.err('Error updating Bisq market price: ' + err); }
 
       const prices: number[] = [];
       trades.forEach((trade) => {

backend/src/api/fiat-conversion.ts

@@ -22,7 +22,7 @@ class FiatConversion {
 
   private updateCurrency() {
     request('https://api.opennode.co/v1/rates', { json: true }, (err, res, body) => {
-      if (err) { return logger.err(err); }
+      if (err) { return logger.err('Error updating currency from OpenNode: ' + err); }
       if (body && body.data) {
         this.tickers = body.data;
       }

backend/src/api/websocket-handler.ts

@@ -107,7 +107,7 @@ class WebsocketHandler {
             client.send(JSON.stringify(response));
           }
         } catch (e) {
-          logger.err(e);
+          logger.err('Error parsing websocket message: ' + e);
         }
       });
     });