improve readability

src/lib/dataSize.ts

@@ -1,11 +1,21 @@
 export function parseDataSize(sizeStr: string): number {
-  if (!sizeStr) return 0;
-  const match = sizeStr.trim().toUpperCase().match(/^([\d.]+)\s*([KMGT]?B)$/);
+  if (typeof sizeStr !== 'string') return 0;
+
+  const match = /^\s*([\d.]+)\s*([KMGT]?B)\s*$/i.exec(sizeStr);
   if (!match) return 0;
-  const [, numStr, unit] = match;
-  const num = parseFloat(numStr) || 0;
-  const multipliers: Record<string, number> = {
-    B: 1, KB: 1024, MB: 1024**2, GB: 1024**3, TB: 1024**4,
-  };
-  return num * (multipliers[unit] || 1);
+
+  const [ , numStr, unitRaw ] = match;
+  const num = parseFloat(numStr);
+  if (isNaN(num)) return 0;
+
+  const unit = unitRaw.toUpperCase();
+  const multipliers = {
+    B: 1,
+    KB: 1024,
+    MB: 1024 ** 2,
+    GB: 1024 ** 3,
+    TB: 1024 ** 4,
+  } as const;
+
+  return num * (multipliers[unit as keyof typeof multipliers] ?? 1);
 }