Be more explicit about device management

src/main.zig

@@ -413,7 +413,13 @@ pub fn main() !void {
     }
     try stdout.flush();
 
-    if (result.devices.len > 0) {
+    switch (result.devices.len) {
+        0 => {
+            try stderr.print("❌ No devices found for user\n", .{});
+            try stderr.flush();
+            return error.NoDevicesFound;
+        },
+        1 => {
             const device = result.devices[0];
 
             if (device.serial_id) |sid| {
@@ -440,5 +446,11 @@ pub fn main() !void {
                 try stderr.flush();
                 return error.NoSerialId;
             }
+        },
+        else => {
+            try stderr.print("❌ More than one device found for user, not currently equipped to handle this\n", .{});
+            try stderr.flush();
+            return error.TooManyDevicesFound;
+        },
     }
 }