diff --git a/wgpu-core/src/resource.rs b/wgpu-core/src/resource.rs
index cd644b003..2e699faa7 100644
--- a/wgpu-core/src/resource.rs
+++ b/wgpu-core/src/resource.rs
@@ -485,101 +485,95 @@ impl<A: HalApi> Buffer<A> {
         size: Option<wgt::BufferAddress>,
         op: BufferMapOperation,
     ) -> Result<(), (BufferMapOperation, BufferAccessError)> {
+        let range_size = if let Some(size) = size {
+            size
+        } else if offset > self.size {
+            0
+        } else {
+            self.size - offset
+        };
+
+        if offset % wgt::MAP_ALIGNMENT != 0 {
+            return Err((op, BufferAccessError::UnalignedOffset { offset }));
+        }
+        if range_size % wgt::COPY_BUFFER_ALIGNMENT != 0 {
+            return Err((op, BufferAccessError::UnalignedRangeSize { range_size }));
+        }
+
+        let range = offset..(offset + range_size);
+
+        if range.start % wgt::MAP_ALIGNMENT != 0 || range.end % wgt::COPY_BUFFER_ALIGNMENT != 0 {
+            return Err((op, BufferAccessError::UnalignedRange));
+        }
+
         let (pub_usage, internal_use) = match op.host {
             HostMap::Read => (wgt::BufferUsages::MAP_READ, hal::BufferUses::MAP_READ),
             HostMap::Write => (wgt::BufferUsages::MAP_WRITE, hal::BufferUses::MAP_WRITE),
         };
 
+        if let Err(e) = crate::validation::check_buffer_usage(self.info.id(), self.usage, pub_usage)
         {
-            {
-                let snatch_guard = self.device.snatchable_lock.read();
-                if self.is_destroyed(&snatch_guard) {
-                    return Err((op, BufferAccessError::Destroyed));
-                }
-            }
-
-            let range_size = if let Some(size) = size {
-                size
-            } else if offset > self.size {
-                0
-            } else {
-                self.size - offset
-            };
-
-            if offset % wgt::MAP_ALIGNMENT != 0 {
-                return Err((op, BufferAccessError::UnalignedOffset { offset }));
-            }
-            if range_size % wgt::COPY_BUFFER_ALIGNMENT != 0 {
-                return Err((op, BufferAccessError::UnalignedRangeSize { range_size }));
-            }
-
-            let range = offset..(offset + range_size);
-
-            if range.start % wgt::MAP_ALIGNMENT != 0 || range.end % wgt::COPY_BUFFER_ALIGNMENT != 0
-            {
-                return Err((op, BufferAccessError::UnalignedRange));
-            }
-
-            let device = &self.device;
-            if !device.is_valid() {
-                return Err((op, DeviceError::Lost.into()));
-            }
-
-            if let Err(e) =
-                crate::validation::check_buffer_usage(self.info.id(), self.usage, pub_usage)
-            {
-                return Err((op, e.into()));
-            }
-
-            if range.start > range.end {
-                return Err((
-                    op,
-                    BufferAccessError::NegativeRange {
-                        start: range.start,
-                        end: range.end,
-                    },
-                ));
-            }
-            if range.end > self.size {
-                return Err((
-                    op,
-                    BufferAccessError::OutOfBoundsOverrun {
-                        index: range.end,
-                        max: self.size,
-                    },
-                ));
-            }
-
-            {
-                let map_state = &mut *self.map_state.lock();
-                *map_state = match *map_state {
-                    BufferMapState::Init { .. } | BufferMapState::Active { .. } => {
-                        return Err((op, BufferAccessError::AlreadyMapped));
-                    }
-                    BufferMapState::Waiting(_) => {
-                        return Err((op, BufferAccessError::MapAlreadyPending));
-                    }
-                    BufferMapState::Idle => BufferMapState::Waiting(BufferPendingMapping {
-                        range,
-                        op,
-                        _parent_buffer: self.clone(),
-                    }),
-                };
-            }
-
-            let snatch_guard = self.device.snatchable_lock.read();
-
-            {
-                let mut trackers = self.device.as_ref().trackers.lock();
-                trackers.buffers.set_single(self, internal_use);
-                //TODO: Check if draining ALL buffers is correct!
-                let _ = trackers.buffers.drain_transitions(&snatch_guard);
-            }
-
-            drop(snatch_guard);
+            return Err((op, e.into()));
         }
 
-        self.device.lock_life().map(self);
+        if range.start > range.end {
+            return Err((
+                op,
+                BufferAccessError::NegativeRange {
+                    start: range.start,
+                    end: range.end,
+                },
+            ));
+        }
+        if range.end > self.size {
+            return Err((
+                op,
+                BufferAccessError::OutOfBoundsOverrun {
+                    index: range.end,
+                    max: self.size,
+                },
+            ));
+        }
+
+        let device = &self.device;
+        if let Err(e) = device.check_is_valid() {
+            return Err((op, e.into()));
+        }
+
+        {
+            let snatch_guard = device.snatchable_lock.read();
+            if self.is_destroyed(&snatch_guard) {
+                return Err((op, BufferAccessError::Destroyed));
+            }
+        }
+
+        {
+            let map_state = &mut *self.map_state.lock();
+            *map_state = match *map_state {
+                BufferMapState::Init { .. } | BufferMapState::Active { .. } => {
+                    return Err((op, BufferAccessError::AlreadyMapped));
+                }
+                BufferMapState::Waiting(_) => {
+                    return Err((op, BufferAccessError::MapAlreadyPending));
+                }
+                BufferMapState::Idle => BufferMapState::Waiting(BufferPendingMapping {
+                    range,
+                    op,
+                    _parent_buffer: self.clone(),
+                }),
+            };
+        }
+
+        let snatch_guard = device.snatchable_lock.read();
+        {
+            let mut trackers = device.as_ref().trackers.lock();
+            trackers.buffers.set_single(self, internal_use);
+            //TODO: Check if draining ALL buffers is correct!
+            let _ = trackers.buffers.drain_transitions(&snatch_guard);
+        }
+        drop(snatch_guard);
+
+        device.lock_life().map(self);
 
         Ok(())
     }