Start with a default to not fail if no swap is present

src/system.js

@@ -151,7 +151,7 @@ async function checkDiskSpace() {
 
 async function getSwapSize() {
     const swaps = await getSwaps();
-    return Object.keys(swaps).map(n => swaps[n].size).reduce((acc, cur) => acc + cur);
+    return Object.keys(swaps).map(n => swaps[n].size).reduce((acc, cur) => acc + cur, 0);
 }
 
 async function getMemory() {